Thermochemistry
ENERGY - the capacity to do work
bull Unlike matter energy is known and recognized by its effectsndash it cannot be seen touched smelled or weighed
bull types of energyndash radiant
(solar energy) energy from the sunndash thermal
the energy associated with the random motion of atoms and molecules (measured by temperature)
ndash chemical
energy stored within the structural units of chemical substancesndash potential
energy available by virtue of an objects position
Conservation of Energy
bull the total quantity of energy in the universe is assumed constant
bull Energy cannot be created or destroyed
bull When one form of energy disappears some other form of energy (of equal magnitude) must appear
ndash The above statements are all saying the same thing
All forms of energy can theoretically convert to other forms of energy
bull Chemical reactions are often utilized in our day-to-day lives not for the products that they produce but for the converted energy that results (ie fuels like natural gas - a chemical reaction results in the transfer of Chemical energy to thermal energy)
bull We do not use the products of the reactionndash Carbon Dioxidendash Water
Hence why there is so much pollution
THERMOCHEMISTRY
ndash Thermochemistry - the study of heat change in chemical reactions
ndash Heat - is the transfer of thermal energy between two bodies that are at different temperatures
Systems and Surroundings (parameters)
ndash When looking at chemical reactions we have to define the system
bull
bull 3 types of systems of Thermochemistry
1open system
2closed system
3isolated systemndash the rest of the universe (outside the system is
called the surroundings)
bull open systems can exchange mass and energybull closed systems allow the transfer of energy (he
at) but not massbull isolated systems do not allow transfer of either
mass or energy
HYDROGEN EXPLOSION - combustion
bull Is this reaction taking place in an open closed or isolated system
bull the reacting mixture is the system (hydrogen oxygen and water molecules) everything else is the surroundings
bull This is exothermic because it is a combustion reaction (thermal energy leaves during this and all other exothermic reaction -- a lot of thermal energy is released in this example)
)(2)(2 222 lOHOgH
open system
Liberating Hydrogen from HClbull Is this reaction taking place in an open closed o
r isolated system
22 HZnClHClZn The gas (hydrogen) is collected and therefore never leaves the system All the matter remains in the system
This is a closed system This system is both exothermic and endothermic Heat is released to the surroundings as Zinc and Chlorine bond together but as hydrogen disassociates from the Chlorine energy is taken in
Whats an example of a chemical reaction occurring in a closed system
bull Examples of Closed Systems
Equations
VP-qE
EQUATIONSCOMBINING
out going means -
in going means remember
wqE
WORKand HEAT
J 1013atm L 1 -convert oremember t
system ain n nexpansiocompressio
VPw
PRACTICE QUESTION
The work done to compress a gas is 74 J As a result 26 J of heat is given off to the surroundings Calculate the change in energy of the gas
Which equation should you use to solve
ANSWER 48 J
Enthalpy (H)
H V
constant remains pressure
ssystem theheat when in change
theof value theas of thought becan
H
VPEH
Most reactions are constant-pressure process Therefore so we can equate the heat change to the change in H
CHANGE IN H
0H EXOTHERMIC
0H CENDOTHERMI
Practice problem
Determine the amount of heat (in kJ) given off when 126 x 10^4 g of NO2 are produced according to the equation
kJ6184
)(NO2)(O)NO(2 22
H
ggg
1146 kJmol
-157 x 10^4 kJ
Practice Problem (for change in Energy)
bull If 20 moles of H2O(g) are converted to H2(g) and O2(g) against a pressure of 10 atm at 125 degrees celsius what is the change in Energy
molkJH
OgHgOH
6483
)(2)(2 222
Calorimetry - the measurement of heat changebull a calorimeter is an insulate
d closed container that creates an ISOLATED SYSTEM
bull a specific quantity of water surrounds a system carrying out a reaction
bull during the reaction heat leaves the system and is absorbed by the surrounding water
bull by recording temperature change the heat generated by a reaction can be recorded
Calorimetrybull Either heat capacity or specific heat must be a
pplied to find a substances change in heatbull Remember
heat capacity specific heat
(C) = m x (s)
tmsqtCq
cc
J
g
J g
bull Heat Capacity ndash heat needed to raise a certain quanity of a su
bstance 1 degree (celsius)
bull Specific Heat ndash the heat needed to raise a 1 gram of a specifi
c substance 1 degree (celsius)
Calorimeter 1 - Constant-Volume Calorimiter (The BOMB Calorimeter)
bull Purpose to collect data on combustible reactions
bull When adding heat to a substance in a Constant-Volume Calorimeters the pressure will increase because the volume has remained the same
bull The substance inside cannot expand
Calorimeter 1 - Constant-Volume Calorimiter (The BOMB Calorimeter)
bull Change of heat of a reaction is qrxn
bull Since the a calorimeter is an isolated system the change in heat of the calorimeter plus water is equal but opposite to the change of heat in the reaction
qsystem = qcal + qrxn = 0Meaning
qcal = -qrxn
Practice Questionbull A quantity of 1435 naphthalene (C10H8) is
burned in a calorimeter The water temp rises from 2028 to 2595 degrees celsius If the heat capacity (C) is 1017 kJcelsius calculate the molar heat combustion of C10
H8bull What is being asked herebull How much heat per mole of napthalene is released into t
he calorimeterTo do
bull Need to figure out how much heat is generated by the combustionbull Need to convert this total heat to q per mole (kJmol)
Practice Question
bull 1922g of methanol (CH3OH) was burned in a calorimeter The temp of water rose by 42 degrees celsius The heat capacity of the system (calorimeter plus water) is 104 kJcelsius Calculate the molar heat of the combustion of methanol
Calorimeter 2 - Constant-Pressure Calorimeter
bull Measures heat changes for non-combustible reaction (ie acid-base reactions)
bull Since the pressure remains the same change in enthalpy equals that to the change in heat
bull Also isolated and filled with water
Specific Heat will be used in calculations Waters specific heat is 4184 Jg(celsius)
ENERGY - the capacity to do work
bull Unlike matter energy is known and recognized by its effectsndash it cannot be seen touched smelled or weighed
bull types of energyndash radiant
(solar energy) energy from the sunndash thermal
the energy associated with the random motion of atoms and molecules (measured by temperature)
ndash chemical
energy stored within the structural units of chemical substancesndash potential
energy available by virtue of an objects position
Conservation of Energy
bull the total quantity of energy in the universe is assumed constant
bull Energy cannot be created or destroyed
bull When one form of energy disappears some other form of energy (of equal magnitude) must appear
ndash The above statements are all saying the same thing
All forms of energy can theoretically convert to other forms of energy
bull Chemical reactions are often utilized in our day-to-day lives not for the products that they produce but for the converted energy that results (ie fuels like natural gas - a chemical reaction results in the transfer of Chemical energy to thermal energy)
bull We do not use the products of the reactionndash Carbon Dioxidendash Water
Hence why there is so much pollution
THERMOCHEMISTRY
ndash Thermochemistry - the study of heat change in chemical reactions
ndash Heat - is the transfer of thermal energy between two bodies that are at different temperatures
Systems and Surroundings (parameters)
ndash When looking at chemical reactions we have to define the system
bull
bull 3 types of systems of Thermochemistry
1open system
2closed system
3isolated systemndash the rest of the universe (outside the system is
called the surroundings)
bull open systems can exchange mass and energybull closed systems allow the transfer of energy (he
at) but not massbull isolated systems do not allow transfer of either
mass or energy
HYDROGEN EXPLOSION - combustion
bull Is this reaction taking place in an open closed or isolated system
bull the reacting mixture is the system (hydrogen oxygen and water molecules) everything else is the surroundings
bull This is exothermic because it is a combustion reaction (thermal energy leaves during this and all other exothermic reaction -- a lot of thermal energy is released in this example)
)(2)(2 222 lOHOgH
open system
Liberating Hydrogen from HClbull Is this reaction taking place in an open closed o
r isolated system
22 HZnClHClZn The gas (hydrogen) is collected and therefore never leaves the system All the matter remains in the system
This is a closed system This system is both exothermic and endothermic Heat is released to the surroundings as Zinc and Chlorine bond together but as hydrogen disassociates from the Chlorine energy is taken in
Whats an example of a chemical reaction occurring in a closed system
bull Examples of Closed Systems
Equations
VP-qE
EQUATIONSCOMBINING
out going means -
in going means remember
wqE
WORKand HEAT
J 1013atm L 1 -convert oremember t
system ain n nexpansiocompressio
VPw
PRACTICE QUESTION
The work done to compress a gas is 74 J As a result 26 J of heat is given off to the surroundings Calculate the change in energy of the gas
Which equation should you use to solve
ANSWER 48 J
Enthalpy (H)
H V
constant remains pressure
ssystem theheat when in change
theof value theas of thought becan
H
VPEH
Most reactions are constant-pressure process Therefore so we can equate the heat change to the change in H
CHANGE IN H
0H EXOTHERMIC
0H CENDOTHERMI
Practice problem
Determine the amount of heat (in kJ) given off when 126 x 10^4 g of NO2 are produced according to the equation
kJ6184
)(NO2)(O)NO(2 22
H
ggg
1146 kJmol
-157 x 10^4 kJ
Practice Problem (for change in Energy)
bull If 20 moles of H2O(g) are converted to H2(g) and O2(g) against a pressure of 10 atm at 125 degrees celsius what is the change in Energy
molkJH
OgHgOH
6483
)(2)(2 222
Calorimetry - the measurement of heat changebull a calorimeter is an insulate
d closed container that creates an ISOLATED SYSTEM
bull a specific quantity of water surrounds a system carrying out a reaction
bull during the reaction heat leaves the system and is absorbed by the surrounding water
bull by recording temperature change the heat generated by a reaction can be recorded
Calorimetrybull Either heat capacity or specific heat must be a
pplied to find a substances change in heatbull Remember
heat capacity specific heat
(C) = m x (s)
tmsqtCq
cc
J
g
J g
bull Heat Capacity ndash heat needed to raise a certain quanity of a su
bstance 1 degree (celsius)
bull Specific Heat ndash the heat needed to raise a 1 gram of a specifi
c substance 1 degree (celsius)
Calorimeter 1 - Constant-Volume Calorimiter (The BOMB Calorimeter)
bull Purpose to collect data on combustible reactions
bull When adding heat to a substance in a Constant-Volume Calorimeters the pressure will increase because the volume has remained the same
bull The substance inside cannot expand
Calorimeter 1 - Constant-Volume Calorimiter (The BOMB Calorimeter)
bull Change of heat of a reaction is qrxn
bull Since the a calorimeter is an isolated system the change in heat of the calorimeter plus water is equal but opposite to the change of heat in the reaction
qsystem = qcal + qrxn = 0Meaning
qcal = -qrxn
Practice Questionbull A quantity of 1435 naphthalene (C10H8) is
burned in a calorimeter The water temp rises from 2028 to 2595 degrees celsius If the heat capacity (C) is 1017 kJcelsius calculate the molar heat combustion of C10
H8bull What is being asked herebull How much heat per mole of napthalene is released into t
he calorimeterTo do
bull Need to figure out how much heat is generated by the combustionbull Need to convert this total heat to q per mole (kJmol)
Practice Question
bull 1922g of methanol (CH3OH) was burned in a calorimeter The temp of water rose by 42 degrees celsius The heat capacity of the system (calorimeter plus water) is 104 kJcelsius Calculate the molar heat of the combustion of methanol
Calorimeter 2 - Constant-Pressure Calorimeter
bull Measures heat changes for non-combustible reaction (ie acid-base reactions)
bull Since the pressure remains the same change in enthalpy equals that to the change in heat
bull Also isolated and filled with water
Specific Heat will be used in calculations Waters specific heat is 4184 Jg(celsius)
Conservation of Energy
bull the total quantity of energy in the universe is assumed constant
bull Energy cannot be created or destroyed
bull When one form of energy disappears some other form of energy (of equal magnitude) must appear
ndash The above statements are all saying the same thing
All forms of energy can theoretically convert to other forms of energy
bull Chemical reactions are often utilized in our day-to-day lives not for the products that they produce but for the converted energy that results (ie fuels like natural gas - a chemical reaction results in the transfer of Chemical energy to thermal energy)
bull We do not use the products of the reactionndash Carbon Dioxidendash Water
Hence why there is so much pollution
THERMOCHEMISTRY
ndash Thermochemistry - the study of heat change in chemical reactions
ndash Heat - is the transfer of thermal energy between two bodies that are at different temperatures
Systems and Surroundings (parameters)
ndash When looking at chemical reactions we have to define the system
bull
bull 3 types of systems of Thermochemistry
1open system
2closed system
3isolated systemndash the rest of the universe (outside the system is
called the surroundings)
bull open systems can exchange mass and energybull closed systems allow the transfer of energy (he
at) but not massbull isolated systems do not allow transfer of either
mass or energy
HYDROGEN EXPLOSION - combustion
bull Is this reaction taking place in an open closed or isolated system
bull the reacting mixture is the system (hydrogen oxygen and water molecules) everything else is the surroundings
bull This is exothermic because it is a combustion reaction (thermal energy leaves during this and all other exothermic reaction -- a lot of thermal energy is released in this example)
)(2)(2 222 lOHOgH
open system
Liberating Hydrogen from HClbull Is this reaction taking place in an open closed o
r isolated system
22 HZnClHClZn The gas (hydrogen) is collected and therefore never leaves the system All the matter remains in the system
This is a closed system This system is both exothermic and endothermic Heat is released to the surroundings as Zinc and Chlorine bond together but as hydrogen disassociates from the Chlorine energy is taken in
Whats an example of a chemical reaction occurring in a closed system
bull Examples of Closed Systems
Equations
VP-qE
EQUATIONSCOMBINING
out going means -
in going means remember
wqE
WORKand HEAT
J 1013atm L 1 -convert oremember t
system ain n nexpansiocompressio
VPw
PRACTICE QUESTION
The work done to compress a gas is 74 J As a result 26 J of heat is given off to the surroundings Calculate the change in energy of the gas
Which equation should you use to solve
ANSWER 48 J
Enthalpy (H)
H V
constant remains pressure
ssystem theheat when in change
theof value theas of thought becan
H
VPEH
Most reactions are constant-pressure process Therefore so we can equate the heat change to the change in H
CHANGE IN H
0H EXOTHERMIC
0H CENDOTHERMI
Practice problem
Determine the amount of heat (in kJ) given off when 126 x 10^4 g of NO2 are produced according to the equation
kJ6184
)(NO2)(O)NO(2 22
H
ggg
1146 kJmol
-157 x 10^4 kJ
Practice Problem (for change in Energy)
bull If 20 moles of H2O(g) are converted to H2(g) and O2(g) against a pressure of 10 atm at 125 degrees celsius what is the change in Energy
molkJH
OgHgOH
6483
)(2)(2 222
Calorimetry - the measurement of heat changebull a calorimeter is an insulate
d closed container that creates an ISOLATED SYSTEM
bull a specific quantity of water surrounds a system carrying out a reaction
bull during the reaction heat leaves the system and is absorbed by the surrounding water
bull by recording temperature change the heat generated by a reaction can be recorded
Calorimetrybull Either heat capacity or specific heat must be a
pplied to find a substances change in heatbull Remember
heat capacity specific heat
(C) = m x (s)
tmsqtCq
cc
J
g
J g
bull Heat Capacity ndash heat needed to raise a certain quanity of a su
bstance 1 degree (celsius)
bull Specific Heat ndash the heat needed to raise a 1 gram of a specifi
c substance 1 degree (celsius)
Calorimeter 1 - Constant-Volume Calorimiter (The BOMB Calorimeter)
bull Purpose to collect data on combustible reactions
bull When adding heat to a substance in a Constant-Volume Calorimeters the pressure will increase because the volume has remained the same
bull The substance inside cannot expand
Calorimeter 1 - Constant-Volume Calorimiter (The BOMB Calorimeter)
bull Change of heat of a reaction is qrxn
bull Since the a calorimeter is an isolated system the change in heat of the calorimeter plus water is equal but opposite to the change of heat in the reaction
qsystem = qcal + qrxn = 0Meaning
qcal = -qrxn
Practice Questionbull A quantity of 1435 naphthalene (C10H8) is
burned in a calorimeter The water temp rises from 2028 to 2595 degrees celsius If the heat capacity (C) is 1017 kJcelsius calculate the molar heat combustion of C10
H8bull What is being asked herebull How much heat per mole of napthalene is released into t
he calorimeterTo do
bull Need to figure out how much heat is generated by the combustionbull Need to convert this total heat to q per mole (kJmol)
Practice Question
bull 1922g of methanol (CH3OH) was burned in a calorimeter The temp of water rose by 42 degrees celsius The heat capacity of the system (calorimeter plus water) is 104 kJcelsius Calculate the molar heat of the combustion of methanol
Calorimeter 2 - Constant-Pressure Calorimeter
bull Measures heat changes for non-combustible reaction (ie acid-base reactions)
bull Since the pressure remains the same change in enthalpy equals that to the change in heat
bull Also isolated and filled with water
Specific Heat will be used in calculations Waters specific heat is 4184 Jg(celsius)
All forms of energy can theoretically convert to other forms of energy
bull Chemical reactions are often utilized in our day-to-day lives not for the products that they produce but for the converted energy that results (ie fuels like natural gas - a chemical reaction results in the transfer of Chemical energy to thermal energy)
bull We do not use the products of the reactionndash Carbon Dioxidendash Water
Hence why there is so much pollution
THERMOCHEMISTRY
ndash Thermochemistry - the study of heat change in chemical reactions
ndash Heat - is the transfer of thermal energy between two bodies that are at different temperatures
Systems and Surroundings (parameters)
ndash When looking at chemical reactions we have to define the system
bull
bull 3 types of systems of Thermochemistry
1open system
2closed system
3isolated systemndash the rest of the universe (outside the system is
called the surroundings)
bull open systems can exchange mass and energybull closed systems allow the transfer of energy (he
at) but not massbull isolated systems do not allow transfer of either
mass or energy
HYDROGEN EXPLOSION - combustion
bull Is this reaction taking place in an open closed or isolated system
bull the reacting mixture is the system (hydrogen oxygen and water molecules) everything else is the surroundings
bull This is exothermic because it is a combustion reaction (thermal energy leaves during this and all other exothermic reaction -- a lot of thermal energy is released in this example)
)(2)(2 222 lOHOgH
open system
Liberating Hydrogen from HClbull Is this reaction taking place in an open closed o
r isolated system
22 HZnClHClZn The gas (hydrogen) is collected and therefore never leaves the system All the matter remains in the system
This is a closed system This system is both exothermic and endothermic Heat is released to the surroundings as Zinc and Chlorine bond together but as hydrogen disassociates from the Chlorine energy is taken in
Whats an example of a chemical reaction occurring in a closed system
bull Examples of Closed Systems
Equations
VP-qE
EQUATIONSCOMBINING
out going means -
in going means remember
wqE
WORKand HEAT
J 1013atm L 1 -convert oremember t
system ain n nexpansiocompressio
VPw
PRACTICE QUESTION
The work done to compress a gas is 74 J As a result 26 J of heat is given off to the surroundings Calculate the change in energy of the gas
Which equation should you use to solve
ANSWER 48 J
Enthalpy (H)
H V
constant remains pressure
ssystem theheat when in change
theof value theas of thought becan
H
VPEH
Most reactions are constant-pressure process Therefore so we can equate the heat change to the change in H
CHANGE IN H
0H EXOTHERMIC
0H CENDOTHERMI
Practice problem
Determine the amount of heat (in kJ) given off when 126 x 10^4 g of NO2 are produced according to the equation
kJ6184
)(NO2)(O)NO(2 22
H
ggg
1146 kJmol
-157 x 10^4 kJ
Practice Problem (for change in Energy)
bull If 20 moles of H2O(g) are converted to H2(g) and O2(g) against a pressure of 10 atm at 125 degrees celsius what is the change in Energy
molkJH
OgHgOH
6483
)(2)(2 222
Calorimetry - the measurement of heat changebull a calorimeter is an insulate
d closed container that creates an ISOLATED SYSTEM
bull a specific quantity of water surrounds a system carrying out a reaction
bull during the reaction heat leaves the system and is absorbed by the surrounding water
bull by recording temperature change the heat generated by a reaction can be recorded
Calorimetrybull Either heat capacity or specific heat must be a
pplied to find a substances change in heatbull Remember
heat capacity specific heat
(C) = m x (s)
tmsqtCq
cc
J
g
J g
bull Heat Capacity ndash heat needed to raise a certain quanity of a su
bstance 1 degree (celsius)
bull Specific Heat ndash the heat needed to raise a 1 gram of a specifi
c substance 1 degree (celsius)
Calorimeter 1 - Constant-Volume Calorimiter (The BOMB Calorimeter)
bull Purpose to collect data on combustible reactions
bull When adding heat to a substance in a Constant-Volume Calorimeters the pressure will increase because the volume has remained the same
bull The substance inside cannot expand
Calorimeter 1 - Constant-Volume Calorimiter (The BOMB Calorimeter)
bull Change of heat of a reaction is qrxn
bull Since the a calorimeter is an isolated system the change in heat of the calorimeter plus water is equal but opposite to the change of heat in the reaction
qsystem = qcal + qrxn = 0Meaning
qcal = -qrxn
Practice Questionbull A quantity of 1435 naphthalene (C10H8) is
burned in a calorimeter The water temp rises from 2028 to 2595 degrees celsius If the heat capacity (C) is 1017 kJcelsius calculate the molar heat combustion of C10
H8bull What is being asked herebull How much heat per mole of napthalene is released into t
he calorimeterTo do
bull Need to figure out how much heat is generated by the combustionbull Need to convert this total heat to q per mole (kJmol)
Practice Question
bull 1922g of methanol (CH3OH) was burned in a calorimeter The temp of water rose by 42 degrees celsius The heat capacity of the system (calorimeter plus water) is 104 kJcelsius Calculate the molar heat of the combustion of methanol
Calorimeter 2 - Constant-Pressure Calorimeter
bull Measures heat changes for non-combustible reaction (ie acid-base reactions)
bull Since the pressure remains the same change in enthalpy equals that to the change in heat
bull Also isolated and filled with water
Specific Heat will be used in calculations Waters specific heat is 4184 Jg(celsius)
THERMOCHEMISTRY
ndash Thermochemistry - the study of heat change in chemical reactions
ndash Heat - is the transfer of thermal energy between two bodies that are at different temperatures
Systems and Surroundings (parameters)
ndash When looking at chemical reactions we have to define the system
bull
bull 3 types of systems of Thermochemistry
1open system
2closed system
3isolated systemndash the rest of the universe (outside the system is
called the surroundings)
bull open systems can exchange mass and energybull closed systems allow the transfer of energy (he
at) but not massbull isolated systems do not allow transfer of either
mass or energy
HYDROGEN EXPLOSION - combustion
bull Is this reaction taking place in an open closed or isolated system
bull the reacting mixture is the system (hydrogen oxygen and water molecules) everything else is the surroundings
bull This is exothermic because it is a combustion reaction (thermal energy leaves during this and all other exothermic reaction -- a lot of thermal energy is released in this example)
)(2)(2 222 lOHOgH
open system
Liberating Hydrogen from HClbull Is this reaction taking place in an open closed o
r isolated system
22 HZnClHClZn The gas (hydrogen) is collected and therefore never leaves the system All the matter remains in the system
This is a closed system This system is both exothermic and endothermic Heat is released to the surroundings as Zinc and Chlorine bond together but as hydrogen disassociates from the Chlorine energy is taken in
Whats an example of a chemical reaction occurring in a closed system
bull Examples of Closed Systems
Equations
VP-qE
EQUATIONSCOMBINING
out going means -
in going means remember
wqE
WORKand HEAT
J 1013atm L 1 -convert oremember t
system ain n nexpansiocompressio
VPw
PRACTICE QUESTION
The work done to compress a gas is 74 J As a result 26 J of heat is given off to the surroundings Calculate the change in energy of the gas
Which equation should you use to solve
ANSWER 48 J
Enthalpy (H)
H V
constant remains pressure
ssystem theheat when in change
theof value theas of thought becan
H
VPEH
Most reactions are constant-pressure process Therefore so we can equate the heat change to the change in H
CHANGE IN H
0H EXOTHERMIC
0H CENDOTHERMI
Practice problem
Determine the amount of heat (in kJ) given off when 126 x 10^4 g of NO2 are produced according to the equation
kJ6184
)(NO2)(O)NO(2 22
H
ggg
1146 kJmol
-157 x 10^4 kJ
Practice Problem (for change in Energy)
bull If 20 moles of H2O(g) are converted to H2(g) and O2(g) against a pressure of 10 atm at 125 degrees celsius what is the change in Energy
molkJH
OgHgOH
6483
)(2)(2 222
Calorimetry - the measurement of heat changebull a calorimeter is an insulate
d closed container that creates an ISOLATED SYSTEM
bull a specific quantity of water surrounds a system carrying out a reaction
bull during the reaction heat leaves the system and is absorbed by the surrounding water
bull by recording temperature change the heat generated by a reaction can be recorded
Calorimetrybull Either heat capacity or specific heat must be a
pplied to find a substances change in heatbull Remember
heat capacity specific heat
(C) = m x (s)
tmsqtCq
cc
J
g
J g
bull Heat Capacity ndash heat needed to raise a certain quanity of a su
bstance 1 degree (celsius)
bull Specific Heat ndash the heat needed to raise a 1 gram of a specifi
c substance 1 degree (celsius)
Calorimeter 1 - Constant-Volume Calorimiter (The BOMB Calorimeter)
bull Purpose to collect data on combustible reactions
bull When adding heat to a substance in a Constant-Volume Calorimeters the pressure will increase because the volume has remained the same
bull The substance inside cannot expand
Calorimeter 1 - Constant-Volume Calorimiter (The BOMB Calorimeter)
bull Change of heat of a reaction is qrxn
bull Since the a calorimeter is an isolated system the change in heat of the calorimeter plus water is equal but opposite to the change of heat in the reaction
qsystem = qcal + qrxn = 0Meaning
qcal = -qrxn
Practice Questionbull A quantity of 1435 naphthalene (C10H8) is
burned in a calorimeter The water temp rises from 2028 to 2595 degrees celsius If the heat capacity (C) is 1017 kJcelsius calculate the molar heat combustion of C10
H8bull What is being asked herebull How much heat per mole of napthalene is released into t
he calorimeterTo do
bull Need to figure out how much heat is generated by the combustionbull Need to convert this total heat to q per mole (kJmol)
Practice Question
bull 1922g of methanol (CH3OH) was burned in a calorimeter The temp of water rose by 42 degrees celsius The heat capacity of the system (calorimeter plus water) is 104 kJcelsius Calculate the molar heat of the combustion of methanol
Calorimeter 2 - Constant-Pressure Calorimeter
bull Measures heat changes for non-combustible reaction (ie acid-base reactions)
bull Since the pressure remains the same change in enthalpy equals that to the change in heat
bull Also isolated and filled with water
Specific Heat will be used in calculations Waters specific heat is 4184 Jg(celsius)
Systems and Surroundings (parameters)
ndash When looking at chemical reactions we have to define the system
bull
bull 3 types of systems of Thermochemistry
1open system
2closed system
3isolated systemndash the rest of the universe (outside the system is
called the surroundings)
bull open systems can exchange mass and energybull closed systems allow the transfer of energy (he
at) but not massbull isolated systems do not allow transfer of either
mass or energy
HYDROGEN EXPLOSION - combustion
bull Is this reaction taking place in an open closed or isolated system
bull the reacting mixture is the system (hydrogen oxygen and water molecules) everything else is the surroundings
bull This is exothermic because it is a combustion reaction (thermal energy leaves during this and all other exothermic reaction -- a lot of thermal energy is released in this example)
)(2)(2 222 lOHOgH
open system
Liberating Hydrogen from HClbull Is this reaction taking place in an open closed o
r isolated system
22 HZnClHClZn The gas (hydrogen) is collected and therefore never leaves the system All the matter remains in the system
This is a closed system This system is both exothermic and endothermic Heat is released to the surroundings as Zinc and Chlorine bond together but as hydrogen disassociates from the Chlorine energy is taken in
Whats an example of a chemical reaction occurring in a closed system
bull Examples of Closed Systems
Equations
VP-qE
EQUATIONSCOMBINING
out going means -
in going means remember
wqE
WORKand HEAT
J 1013atm L 1 -convert oremember t
system ain n nexpansiocompressio
VPw
PRACTICE QUESTION
The work done to compress a gas is 74 J As a result 26 J of heat is given off to the surroundings Calculate the change in energy of the gas
Which equation should you use to solve
ANSWER 48 J
Enthalpy (H)
H V
constant remains pressure
ssystem theheat when in change
theof value theas of thought becan
H
VPEH
Most reactions are constant-pressure process Therefore so we can equate the heat change to the change in H
CHANGE IN H
0H EXOTHERMIC
0H CENDOTHERMI
Practice problem
Determine the amount of heat (in kJ) given off when 126 x 10^4 g of NO2 are produced according to the equation
kJ6184
)(NO2)(O)NO(2 22
H
ggg
1146 kJmol
-157 x 10^4 kJ
Practice Problem (for change in Energy)
bull If 20 moles of H2O(g) are converted to H2(g) and O2(g) against a pressure of 10 atm at 125 degrees celsius what is the change in Energy
molkJH
OgHgOH
6483
)(2)(2 222
Calorimetry - the measurement of heat changebull a calorimeter is an insulate
d closed container that creates an ISOLATED SYSTEM
bull a specific quantity of water surrounds a system carrying out a reaction
bull during the reaction heat leaves the system and is absorbed by the surrounding water
bull by recording temperature change the heat generated by a reaction can be recorded
Calorimetrybull Either heat capacity or specific heat must be a
pplied to find a substances change in heatbull Remember
heat capacity specific heat
(C) = m x (s)
tmsqtCq
cc
J
g
J g
bull Heat Capacity ndash heat needed to raise a certain quanity of a su
bstance 1 degree (celsius)
bull Specific Heat ndash the heat needed to raise a 1 gram of a specifi
c substance 1 degree (celsius)
Calorimeter 1 - Constant-Volume Calorimiter (The BOMB Calorimeter)
bull Purpose to collect data on combustible reactions
bull When adding heat to a substance in a Constant-Volume Calorimeters the pressure will increase because the volume has remained the same
bull The substance inside cannot expand
Calorimeter 1 - Constant-Volume Calorimiter (The BOMB Calorimeter)
bull Change of heat of a reaction is qrxn
bull Since the a calorimeter is an isolated system the change in heat of the calorimeter plus water is equal but opposite to the change of heat in the reaction
qsystem = qcal + qrxn = 0Meaning
qcal = -qrxn
Practice Questionbull A quantity of 1435 naphthalene (C10H8) is
burned in a calorimeter The water temp rises from 2028 to 2595 degrees celsius If the heat capacity (C) is 1017 kJcelsius calculate the molar heat combustion of C10
H8bull What is being asked herebull How much heat per mole of napthalene is released into t
he calorimeterTo do
bull Need to figure out how much heat is generated by the combustionbull Need to convert this total heat to q per mole (kJmol)
Practice Question
bull 1922g of methanol (CH3OH) was burned in a calorimeter The temp of water rose by 42 degrees celsius The heat capacity of the system (calorimeter plus water) is 104 kJcelsius Calculate the molar heat of the combustion of methanol
Calorimeter 2 - Constant-Pressure Calorimeter
bull Measures heat changes for non-combustible reaction (ie acid-base reactions)
bull Since the pressure remains the same change in enthalpy equals that to the change in heat
bull Also isolated and filled with water
Specific Heat will be used in calculations Waters specific heat is 4184 Jg(celsius)
bull open systems can exchange mass and energybull closed systems allow the transfer of energy (he
at) but not massbull isolated systems do not allow transfer of either
mass or energy
HYDROGEN EXPLOSION - combustion
bull Is this reaction taking place in an open closed or isolated system
bull the reacting mixture is the system (hydrogen oxygen and water molecules) everything else is the surroundings
bull This is exothermic because it is a combustion reaction (thermal energy leaves during this and all other exothermic reaction -- a lot of thermal energy is released in this example)
)(2)(2 222 lOHOgH
open system
Liberating Hydrogen from HClbull Is this reaction taking place in an open closed o
r isolated system
22 HZnClHClZn The gas (hydrogen) is collected and therefore never leaves the system All the matter remains in the system
This is a closed system This system is both exothermic and endothermic Heat is released to the surroundings as Zinc and Chlorine bond together but as hydrogen disassociates from the Chlorine energy is taken in
Whats an example of a chemical reaction occurring in a closed system
bull Examples of Closed Systems
Equations
VP-qE
EQUATIONSCOMBINING
out going means -
in going means remember
wqE
WORKand HEAT
J 1013atm L 1 -convert oremember t
system ain n nexpansiocompressio
VPw
PRACTICE QUESTION
The work done to compress a gas is 74 J As a result 26 J of heat is given off to the surroundings Calculate the change in energy of the gas
Which equation should you use to solve
ANSWER 48 J
Enthalpy (H)
H V
constant remains pressure
ssystem theheat when in change
theof value theas of thought becan
H
VPEH
Most reactions are constant-pressure process Therefore so we can equate the heat change to the change in H
CHANGE IN H
0H EXOTHERMIC
0H CENDOTHERMI
Practice problem
Determine the amount of heat (in kJ) given off when 126 x 10^4 g of NO2 are produced according to the equation
kJ6184
)(NO2)(O)NO(2 22
H
ggg
1146 kJmol
-157 x 10^4 kJ
Practice Problem (for change in Energy)
bull If 20 moles of H2O(g) are converted to H2(g) and O2(g) against a pressure of 10 atm at 125 degrees celsius what is the change in Energy
molkJH
OgHgOH
6483
)(2)(2 222
Calorimetry - the measurement of heat changebull a calorimeter is an insulate
d closed container that creates an ISOLATED SYSTEM
bull a specific quantity of water surrounds a system carrying out a reaction
bull during the reaction heat leaves the system and is absorbed by the surrounding water
bull by recording temperature change the heat generated by a reaction can be recorded
Calorimetrybull Either heat capacity or specific heat must be a
pplied to find a substances change in heatbull Remember
heat capacity specific heat
(C) = m x (s)
tmsqtCq
cc
J
g
J g
bull Heat Capacity ndash heat needed to raise a certain quanity of a su
bstance 1 degree (celsius)
bull Specific Heat ndash the heat needed to raise a 1 gram of a specifi
c substance 1 degree (celsius)
Calorimeter 1 - Constant-Volume Calorimiter (The BOMB Calorimeter)
bull Purpose to collect data on combustible reactions
bull When adding heat to a substance in a Constant-Volume Calorimeters the pressure will increase because the volume has remained the same
bull The substance inside cannot expand
Calorimeter 1 - Constant-Volume Calorimiter (The BOMB Calorimeter)
bull Change of heat of a reaction is qrxn
bull Since the a calorimeter is an isolated system the change in heat of the calorimeter plus water is equal but opposite to the change of heat in the reaction
qsystem = qcal + qrxn = 0Meaning
qcal = -qrxn
Practice Questionbull A quantity of 1435 naphthalene (C10H8) is
burned in a calorimeter The water temp rises from 2028 to 2595 degrees celsius If the heat capacity (C) is 1017 kJcelsius calculate the molar heat combustion of C10
H8bull What is being asked herebull How much heat per mole of napthalene is released into t
he calorimeterTo do
bull Need to figure out how much heat is generated by the combustionbull Need to convert this total heat to q per mole (kJmol)
Practice Question
bull 1922g of methanol (CH3OH) was burned in a calorimeter The temp of water rose by 42 degrees celsius The heat capacity of the system (calorimeter plus water) is 104 kJcelsius Calculate the molar heat of the combustion of methanol
Calorimeter 2 - Constant-Pressure Calorimeter
bull Measures heat changes for non-combustible reaction (ie acid-base reactions)
bull Since the pressure remains the same change in enthalpy equals that to the change in heat
bull Also isolated and filled with water
Specific Heat will be used in calculations Waters specific heat is 4184 Jg(celsius)
HYDROGEN EXPLOSION - combustion
bull Is this reaction taking place in an open closed or isolated system
bull the reacting mixture is the system (hydrogen oxygen and water molecules) everything else is the surroundings
bull This is exothermic because it is a combustion reaction (thermal energy leaves during this and all other exothermic reaction -- a lot of thermal energy is released in this example)
)(2)(2 222 lOHOgH
open system
Liberating Hydrogen from HClbull Is this reaction taking place in an open closed o
r isolated system
22 HZnClHClZn The gas (hydrogen) is collected and therefore never leaves the system All the matter remains in the system
This is a closed system This system is both exothermic and endothermic Heat is released to the surroundings as Zinc and Chlorine bond together but as hydrogen disassociates from the Chlorine energy is taken in
Whats an example of a chemical reaction occurring in a closed system
bull Examples of Closed Systems
Equations
VP-qE
EQUATIONSCOMBINING
out going means -
in going means remember
wqE
WORKand HEAT
J 1013atm L 1 -convert oremember t
system ain n nexpansiocompressio
VPw
PRACTICE QUESTION
The work done to compress a gas is 74 J As a result 26 J of heat is given off to the surroundings Calculate the change in energy of the gas
Which equation should you use to solve
ANSWER 48 J
Enthalpy (H)
H V
constant remains pressure
ssystem theheat when in change
theof value theas of thought becan
H
VPEH
Most reactions are constant-pressure process Therefore so we can equate the heat change to the change in H
CHANGE IN H
0H EXOTHERMIC
0H CENDOTHERMI
Practice problem
Determine the amount of heat (in kJ) given off when 126 x 10^4 g of NO2 are produced according to the equation
kJ6184
)(NO2)(O)NO(2 22
H
ggg
1146 kJmol
-157 x 10^4 kJ
Practice Problem (for change in Energy)
bull If 20 moles of H2O(g) are converted to H2(g) and O2(g) against a pressure of 10 atm at 125 degrees celsius what is the change in Energy
molkJH
OgHgOH
6483
)(2)(2 222
Calorimetry - the measurement of heat changebull a calorimeter is an insulate
d closed container that creates an ISOLATED SYSTEM
bull a specific quantity of water surrounds a system carrying out a reaction
bull during the reaction heat leaves the system and is absorbed by the surrounding water
bull by recording temperature change the heat generated by a reaction can be recorded
Calorimetrybull Either heat capacity or specific heat must be a
pplied to find a substances change in heatbull Remember
heat capacity specific heat
(C) = m x (s)
tmsqtCq
cc
J
g
J g
bull Heat Capacity ndash heat needed to raise a certain quanity of a su
bstance 1 degree (celsius)
bull Specific Heat ndash the heat needed to raise a 1 gram of a specifi
c substance 1 degree (celsius)
Calorimeter 1 - Constant-Volume Calorimiter (The BOMB Calorimeter)
bull Purpose to collect data on combustible reactions
bull When adding heat to a substance in a Constant-Volume Calorimeters the pressure will increase because the volume has remained the same
bull The substance inside cannot expand
Calorimeter 1 - Constant-Volume Calorimiter (The BOMB Calorimeter)
bull Change of heat of a reaction is qrxn
bull Since the a calorimeter is an isolated system the change in heat of the calorimeter plus water is equal but opposite to the change of heat in the reaction
qsystem = qcal + qrxn = 0Meaning
qcal = -qrxn
Practice Questionbull A quantity of 1435 naphthalene (C10H8) is
burned in a calorimeter The water temp rises from 2028 to 2595 degrees celsius If the heat capacity (C) is 1017 kJcelsius calculate the molar heat combustion of C10
H8bull What is being asked herebull How much heat per mole of napthalene is released into t
he calorimeterTo do
bull Need to figure out how much heat is generated by the combustionbull Need to convert this total heat to q per mole (kJmol)
Practice Question
bull 1922g of methanol (CH3OH) was burned in a calorimeter The temp of water rose by 42 degrees celsius The heat capacity of the system (calorimeter plus water) is 104 kJcelsius Calculate the molar heat of the combustion of methanol
Calorimeter 2 - Constant-Pressure Calorimeter
bull Measures heat changes for non-combustible reaction (ie acid-base reactions)
bull Since the pressure remains the same change in enthalpy equals that to the change in heat
bull Also isolated and filled with water
Specific Heat will be used in calculations Waters specific heat is 4184 Jg(celsius)
Liberating Hydrogen from HClbull Is this reaction taking place in an open closed o
r isolated system
22 HZnClHClZn The gas (hydrogen) is collected and therefore never leaves the system All the matter remains in the system
This is a closed system This system is both exothermic and endothermic Heat is released to the surroundings as Zinc and Chlorine bond together but as hydrogen disassociates from the Chlorine energy is taken in
Whats an example of a chemical reaction occurring in a closed system
bull Examples of Closed Systems
Equations
VP-qE
EQUATIONSCOMBINING
out going means -
in going means remember
wqE
WORKand HEAT
J 1013atm L 1 -convert oremember t
system ain n nexpansiocompressio
VPw
PRACTICE QUESTION
The work done to compress a gas is 74 J As a result 26 J of heat is given off to the surroundings Calculate the change in energy of the gas
Which equation should you use to solve
ANSWER 48 J
Enthalpy (H)
H V
constant remains pressure
ssystem theheat when in change
theof value theas of thought becan
H
VPEH
Most reactions are constant-pressure process Therefore so we can equate the heat change to the change in H
CHANGE IN H
0H EXOTHERMIC
0H CENDOTHERMI
Practice problem
Determine the amount of heat (in kJ) given off when 126 x 10^4 g of NO2 are produced according to the equation
kJ6184
)(NO2)(O)NO(2 22
H
ggg
1146 kJmol
-157 x 10^4 kJ
Practice Problem (for change in Energy)
bull If 20 moles of H2O(g) are converted to H2(g) and O2(g) against a pressure of 10 atm at 125 degrees celsius what is the change in Energy
molkJH
OgHgOH
6483
)(2)(2 222
Calorimetry - the measurement of heat changebull a calorimeter is an insulate
d closed container that creates an ISOLATED SYSTEM
bull a specific quantity of water surrounds a system carrying out a reaction
bull during the reaction heat leaves the system and is absorbed by the surrounding water
bull by recording temperature change the heat generated by a reaction can be recorded
Calorimetrybull Either heat capacity or specific heat must be a
pplied to find a substances change in heatbull Remember
heat capacity specific heat
(C) = m x (s)
tmsqtCq
cc
J
g
J g
bull Heat Capacity ndash heat needed to raise a certain quanity of a su
bstance 1 degree (celsius)
bull Specific Heat ndash the heat needed to raise a 1 gram of a specifi
c substance 1 degree (celsius)
Calorimeter 1 - Constant-Volume Calorimiter (The BOMB Calorimeter)
bull Purpose to collect data on combustible reactions
bull When adding heat to a substance in a Constant-Volume Calorimeters the pressure will increase because the volume has remained the same
bull The substance inside cannot expand
Calorimeter 1 - Constant-Volume Calorimiter (The BOMB Calorimeter)
bull Change of heat of a reaction is qrxn
bull Since the a calorimeter is an isolated system the change in heat of the calorimeter plus water is equal but opposite to the change of heat in the reaction
qsystem = qcal + qrxn = 0Meaning
qcal = -qrxn
Practice Questionbull A quantity of 1435 naphthalene (C10H8) is
burned in a calorimeter The water temp rises from 2028 to 2595 degrees celsius If the heat capacity (C) is 1017 kJcelsius calculate the molar heat combustion of C10
H8bull What is being asked herebull How much heat per mole of napthalene is released into t
he calorimeterTo do
bull Need to figure out how much heat is generated by the combustionbull Need to convert this total heat to q per mole (kJmol)
Practice Question
bull 1922g of methanol (CH3OH) was burned in a calorimeter The temp of water rose by 42 degrees celsius The heat capacity of the system (calorimeter plus water) is 104 kJcelsius Calculate the molar heat of the combustion of methanol
Calorimeter 2 - Constant-Pressure Calorimeter
bull Measures heat changes for non-combustible reaction (ie acid-base reactions)
bull Since the pressure remains the same change in enthalpy equals that to the change in heat
bull Also isolated and filled with water
Specific Heat will be used in calculations Waters specific heat is 4184 Jg(celsius)
Whats an example of a chemical reaction occurring in a closed system
bull Examples of Closed Systems
Equations
VP-qE
EQUATIONSCOMBINING
out going means -
in going means remember
wqE
WORKand HEAT
J 1013atm L 1 -convert oremember t
system ain n nexpansiocompressio
VPw
PRACTICE QUESTION
The work done to compress a gas is 74 J As a result 26 J of heat is given off to the surroundings Calculate the change in energy of the gas
Which equation should you use to solve
ANSWER 48 J
Enthalpy (H)
H V
constant remains pressure
ssystem theheat when in change
theof value theas of thought becan
H
VPEH
Most reactions are constant-pressure process Therefore so we can equate the heat change to the change in H
CHANGE IN H
0H EXOTHERMIC
0H CENDOTHERMI
Practice problem
Determine the amount of heat (in kJ) given off when 126 x 10^4 g of NO2 are produced according to the equation
kJ6184
)(NO2)(O)NO(2 22
H
ggg
1146 kJmol
-157 x 10^4 kJ
Practice Problem (for change in Energy)
bull If 20 moles of H2O(g) are converted to H2(g) and O2(g) against a pressure of 10 atm at 125 degrees celsius what is the change in Energy
molkJH
OgHgOH
6483
)(2)(2 222
Calorimetry - the measurement of heat changebull a calorimeter is an insulate
d closed container that creates an ISOLATED SYSTEM
bull a specific quantity of water surrounds a system carrying out a reaction
bull during the reaction heat leaves the system and is absorbed by the surrounding water
bull by recording temperature change the heat generated by a reaction can be recorded
Calorimetrybull Either heat capacity or specific heat must be a
pplied to find a substances change in heatbull Remember
heat capacity specific heat
(C) = m x (s)
tmsqtCq
cc
J
g
J g
bull Heat Capacity ndash heat needed to raise a certain quanity of a su
bstance 1 degree (celsius)
bull Specific Heat ndash the heat needed to raise a 1 gram of a specifi
c substance 1 degree (celsius)
Calorimeter 1 - Constant-Volume Calorimiter (The BOMB Calorimeter)
bull Purpose to collect data on combustible reactions
bull When adding heat to a substance in a Constant-Volume Calorimeters the pressure will increase because the volume has remained the same
bull The substance inside cannot expand
Calorimeter 1 - Constant-Volume Calorimiter (The BOMB Calorimeter)
bull Change of heat of a reaction is qrxn
bull Since the a calorimeter is an isolated system the change in heat of the calorimeter plus water is equal but opposite to the change of heat in the reaction
qsystem = qcal + qrxn = 0Meaning
qcal = -qrxn
Practice Questionbull A quantity of 1435 naphthalene (C10H8) is
burned in a calorimeter The water temp rises from 2028 to 2595 degrees celsius If the heat capacity (C) is 1017 kJcelsius calculate the molar heat combustion of C10
H8bull What is being asked herebull How much heat per mole of napthalene is released into t
he calorimeterTo do
bull Need to figure out how much heat is generated by the combustionbull Need to convert this total heat to q per mole (kJmol)
Practice Question
bull 1922g of methanol (CH3OH) was burned in a calorimeter The temp of water rose by 42 degrees celsius The heat capacity of the system (calorimeter plus water) is 104 kJcelsius Calculate the molar heat of the combustion of methanol
Calorimeter 2 - Constant-Pressure Calorimeter
bull Measures heat changes for non-combustible reaction (ie acid-base reactions)
bull Since the pressure remains the same change in enthalpy equals that to the change in heat
bull Also isolated and filled with water
Specific Heat will be used in calculations Waters specific heat is 4184 Jg(celsius)
Equations
VP-qE
EQUATIONSCOMBINING
out going means -
in going means remember
wqE
WORKand HEAT
J 1013atm L 1 -convert oremember t
system ain n nexpansiocompressio
VPw
PRACTICE QUESTION
The work done to compress a gas is 74 J As a result 26 J of heat is given off to the surroundings Calculate the change in energy of the gas
Which equation should you use to solve
ANSWER 48 J
Enthalpy (H)
H V
constant remains pressure
ssystem theheat when in change
theof value theas of thought becan
H
VPEH
Most reactions are constant-pressure process Therefore so we can equate the heat change to the change in H
CHANGE IN H
0H EXOTHERMIC
0H CENDOTHERMI
Practice problem
Determine the amount of heat (in kJ) given off when 126 x 10^4 g of NO2 are produced according to the equation
kJ6184
)(NO2)(O)NO(2 22
H
ggg
1146 kJmol
-157 x 10^4 kJ
Practice Problem (for change in Energy)
bull If 20 moles of H2O(g) are converted to H2(g) and O2(g) against a pressure of 10 atm at 125 degrees celsius what is the change in Energy
molkJH
OgHgOH
6483
)(2)(2 222
Calorimetry - the measurement of heat changebull a calorimeter is an insulate
d closed container that creates an ISOLATED SYSTEM
bull a specific quantity of water surrounds a system carrying out a reaction
bull during the reaction heat leaves the system and is absorbed by the surrounding water
bull by recording temperature change the heat generated by a reaction can be recorded
Calorimetrybull Either heat capacity or specific heat must be a
pplied to find a substances change in heatbull Remember
heat capacity specific heat
(C) = m x (s)
tmsqtCq
cc
J
g
J g
bull Heat Capacity ndash heat needed to raise a certain quanity of a su
bstance 1 degree (celsius)
bull Specific Heat ndash the heat needed to raise a 1 gram of a specifi
c substance 1 degree (celsius)
Calorimeter 1 - Constant-Volume Calorimiter (The BOMB Calorimeter)
bull Purpose to collect data on combustible reactions
bull When adding heat to a substance in a Constant-Volume Calorimeters the pressure will increase because the volume has remained the same
bull The substance inside cannot expand
Calorimeter 1 - Constant-Volume Calorimiter (The BOMB Calorimeter)
bull Change of heat of a reaction is qrxn
bull Since the a calorimeter is an isolated system the change in heat of the calorimeter plus water is equal but opposite to the change of heat in the reaction
qsystem = qcal + qrxn = 0Meaning
qcal = -qrxn
Practice Questionbull A quantity of 1435 naphthalene (C10H8) is
burned in a calorimeter The water temp rises from 2028 to 2595 degrees celsius If the heat capacity (C) is 1017 kJcelsius calculate the molar heat combustion of C10
H8bull What is being asked herebull How much heat per mole of napthalene is released into t
he calorimeterTo do
bull Need to figure out how much heat is generated by the combustionbull Need to convert this total heat to q per mole (kJmol)
Practice Question
bull 1922g of methanol (CH3OH) was burned in a calorimeter The temp of water rose by 42 degrees celsius The heat capacity of the system (calorimeter plus water) is 104 kJcelsius Calculate the molar heat of the combustion of methanol
Calorimeter 2 - Constant-Pressure Calorimeter
bull Measures heat changes for non-combustible reaction (ie acid-base reactions)
bull Since the pressure remains the same change in enthalpy equals that to the change in heat
bull Also isolated and filled with water
Specific Heat will be used in calculations Waters specific heat is 4184 Jg(celsius)
Enthalpy (H)
H V
constant remains pressure
ssystem theheat when in change
theof value theas of thought becan
H
VPEH
Most reactions are constant-pressure process Therefore so we can equate the heat change to the change in H
CHANGE IN H
0H EXOTHERMIC
0H CENDOTHERMI
Practice problem
Determine the amount of heat (in kJ) given off when 126 x 10^4 g of NO2 are produced according to the equation
kJ6184
)(NO2)(O)NO(2 22
H
ggg
1146 kJmol
-157 x 10^4 kJ
Practice Problem (for change in Energy)
bull If 20 moles of H2O(g) are converted to H2(g) and O2(g) against a pressure of 10 atm at 125 degrees celsius what is the change in Energy
molkJH
OgHgOH
6483
)(2)(2 222
Calorimetry - the measurement of heat changebull a calorimeter is an insulate
d closed container that creates an ISOLATED SYSTEM
bull a specific quantity of water surrounds a system carrying out a reaction
bull during the reaction heat leaves the system and is absorbed by the surrounding water
bull by recording temperature change the heat generated by a reaction can be recorded
Calorimetrybull Either heat capacity or specific heat must be a
pplied to find a substances change in heatbull Remember
heat capacity specific heat
(C) = m x (s)
tmsqtCq
cc
J
g
J g
bull Heat Capacity ndash heat needed to raise a certain quanity of a su
bstance 1 degree (celsius)
bull Specific Heat ndash the heat needed to raise a 1 gram of a specifi
c substance 1 degree (celsius)
Calorimeter 1 - Constant-Volume Calorimiter (The BOMB Calorimeter)
bull Purpose to collect data on combustible reactions
bull When adding heat to a substance in a Constant-Volume Calorimeters the pressure will increase because the volume has remained the same
bull The substance inside cannot expand
Calorimeter 1 - Constant-Volume Calorimiter (The BOMB Calorimeter)
bull Change of heat of a reaction is qrxn
bull Since the a calorimeter is an isolated system the change in heat of the calorimeter plus water is equal but opposite to the change of heat in the reaction
qsystem = qcal + qrxn = 0Meaning
qcal = -qrxn
Practice Questionbull A quantity of 1435 naphthalene (C10H8) is
burned in a calorimeter The water temp rises from 2028 to 2595 degrees celsius If the heat capacity (C) is 1017 kJcelsius calculate the molar heat combustion of C10
H8bull What is being asked herebull How much heat per mole of napthalene is released into t
he calorimeterTo do
bull Need to figure out how much heat is generated by the combustionbull Need to convert this total heat to q per mole (kJmol)
Practice Question
bull 1922g of methanol (CH3OH) was burned in a calorimeter The temp of water rose by 42 degrees celsius The heat capacity of the system (calorimeter plus water) is 104 kJcelsius Calculate the molar heat of the combustion of methanol
Calorimeter 2 - Constant-Pressure Calorimeter
bull Measures heat changes for non-combustible reaction (ie acid-base reactions)
bull Since the pressure remains the same change in enthalpy equals that to the change in heat
bull Also isolated and filled with water
Specific Heat will be used in calculations Waters specific heat is 4184 Jg(celsius)
CHANGE IN H
0H EXOTHERMIC
0H CENDOTHERMI
Practice problem
Determine the amount of heat (in kJ) given off when 126 x 10^4 g of NO2 are produced according to the equation
kJ6184
)(NO2)(O)NO(2 22
H
ggg
1146 kJmol
-157 x 10^4 kJ
Practice Problem (for change in Energy)
bull If 20 moles of H2O(g) are converted to H2(g) and O2(g) against a pressure of 10 atm at 125 degrees celsius what is the change in Energy
molkJH
OgHgOH
6483
)(2)(2 222
Calorimetry - the measurement of heat changebull a calorimeter is an insulate
d closed container that creates an ISOLATED SYSTEM
bull a specific quantity of water surrounds a system carrying out a reaction
bull during the reaction heat leaves the system and is absorbed by the surrounding water
bull by recording temperature change the heat generated by a reaction can be recorded
Calorimetrybull Either heat capacity or specific heat must be a
pplied to find a substances change in heatbull Remember
heat capacity specific heat
(C) = m x (s)
tmsqtCq
cc
J
g
J g
bull Heat Capacity ndash heat needed to raise a certain quanity of a su
bstance 1 degree (celsius)
bull Specific Heat ndash the heat needed to raise a 1 gram of a specifi
c substance 1 degree (celsius)
Calorimeter 1 - Constant-Volume Calorimiter (The BOMB Calorimeter)
bull Purpose to collect data on combustible reactions
bull When adding heat to a substance in a Constant-Volume Calorimeters the pressure will increase because the volume has remained the same
bull The substance inside cannot expand
Calorimeter 1 - Constant-Volume Calorimiter (The BOMB Calorimeter)
bull Change of heat of a reaction is qrxn
bull Since the a calorimeter is an isolated system the change in heat of the calorimeter plus water is equal but opposite to the change of heat in the reaction
qsystem = qcal + qrxn = 0Meaning
qcal = -qrxn
Practice Questionbull A quantity of 1435 naphthalene (C10H8) is
burned in a calorimeter The water temp rises from 2028 to 2595 degrees celsius If the heat capacity (C) is 1017 kJcelsius calculate the molar heat combustion of C10
H8bull What is being asked herebull How much heat per mole of napthalene is released into t
he calorimeterTo do
bull Need to figure out how much heat is generated by the combustionbull Need to convert this total heat to q per mole (kJmol)
Practice Question
bull 1922g of methanol (CH3OH) was burned in a calorimeter The temp of water rose by 42 degrees celsius The heat capacity of the system (calorimeter plus water) is 104 kJcelsius Calculate the molar heat of the combustion of methanol
Calorimeter 2 - Constant-Pressure Calorimeter
bull Measures heat changes for non-combustible reaction (ie acid-base reactions)
bull Since the pressure remains the same change in enthalpy equals that to the change in heat
bull Also isolated and filled with water
Specific Heat will be used in calculations Waters specific heat is 4184 Jg(celsius)
Practice problem
Determine the amount of heat (in kJ) given off when 126 x 10^4 g of NO2 are produced according to the equation
kJ6184
)(NO2)(O)NO(2 22
H
ggg
1146 kJmol
-157 x 10^4 kJ
Practice Problem (for change in Energy)
bull If 20 moles of H2O(g) are converted to H2(g) and O2(g) against a pressure of 10 atm at 125 degrees celsius what is the change in Energy
molkJH
OgHgOH
6483
)(2)(2 222
Calorimetry - the measurement of heat changebull a calorimeter is an insulate
d closed container that creates an ISOLATED SYSTEM
bull a specific quantity of water surrounds a system carrying out a reaction
bull during the reaction heat leaves the system and is absorbed by the surrounding water
bull by recording temperature change the heat generated by a reaction can be recorded
Calorimetrybull Either heat capacity or specific heat must be a
pplied to find a substances change in heatbull Remember
heat capacity specific heat
(C) = m x (s)
tmsqtCq
cc
J
g
J g
bull Heat Capacity ndash heat needed to raise a certain quanity of a su
bstance 1 degree (celsius)
bull Specific Heat ndash the heat needed to raise a 1 gram of a specifi
c substance 1 degree (celsius)
Calorimeter 1 - Constant-Volume Calorimiter (The BOMB Calorimeter)
bull Purpose to collect data on combustible reactions
bull When adding heat to a substance in a Constant-Volume Calorimeters the pressure will increase because the volume has remained the same
bull The substance inside cannot expand
Calorimeter 1 - Constant-Volume Calorimiter (The BOMB Calorimeter)
bull Change of heat of a reaction is qrxn
bull Since the a calorimeter is an isolated system the change in heat of the calorimeter plus water is equal but opposite to the change of heat in the reaction
qsystem = qcal + qrxn = 0Meaning
qcal = -qrxn
Practice Questionbull A quantity of 1435 naphthalene (C10H8) is
burned in a calorimeter The water temp rises from 2028 to 2595 degrees celsius If the heat capacity (C) is 1017 kJcelsius calculate the molar heat combustion of C10
H8bull What is being asked herebull How much heat per mole of napthalene is released into t
he calorimeterTo do
bull Need to figure out how much heat is generated by the combustionbull Need to convert this total heat to q per mole (kJmol)
Practice Question
bull 1922g of methanol (CH3OH) was burned in a calorimeter The temp of water rose by 42 degrees celsius The heat capacity of the system (calorimeter plus water) is 104 kJcelsius Calculate the molar heat of the combustion of methanol
Calorimeter 2 - Constant-Pressure Calorimeter
bull Measures heat changes for non-combustible reaction (ie acid-base reactions)
bull Since the pressure remains the same change in enthalpy equals that to the change in heat
bull Also isolated and filled with water
Specific Heat will be used in calculations Waters specific heat is 4184 Jg(celsius)
Practice Problem (for change in Energy)
bull If 20 moles of H2O(g) are converted to H2(g) and O2(g) against a pressure of 10 atm at 125 degrees celsius what is the change in Energy
molkJH
OgHgOH
6483
)(2)(2 222
Calorimetry - the measurement of heat changebull a calorimeter is an insulate
d closed container that creates an ISOLATED SYSTEM
bull a specific quantity of water surrounds a system carrying out a reaction
bull during the reaction heat leaves the system and is absorbed by the surrounding water
bull by recording temperature change the heat generated by a reaction can be recorded
Calorimetrybull Either heat capacity or specific heat must be a
pplied to find a substances change in heatbull Remember
heat capacity specific heat
(C) = m x (s)
tmsqtCq
cc
J
g
J g
bull Heat Capacity ndash heat needed to raise a certain quanity of a su
bstance 1 degree (celsius)
bull Specific Heat ndash the heat needed to raise a 1 gram of a specifi
c substance 1 degree (celsius)
Calorimeter 1 - Constant-Volume Calorimiter (The BOMB Calorimeter)
bull Purpose to collect data on combustible reactions
bull When adding heat to a substance in a Constant-Volume Calorimeters the pressure will increase because the volume has remained the same
bull The substance inside cannot expand
Calorimeter 1 - Constant-Volume Calorimiter (The BOMB Calorimeter)
bull Change of heat of a reaction is qrxn
bull Since the a calorimeter is an isolated system the change in heat of the calorimeter plus water is equal but opposite to the change of heat in the reaction
qsystem = qcal + qrxn = 0Meaning
qcal = -qrxn
Practice Questionbull A quantity of 1435 naphthalene (C10H8) is
burned in a calorimeter The water temp rises from 2028 to 2595 degrees celsius If the heat capacity (C) is 1017 kJcelsius calculate the molar heat combustion of C10
H8bull What is being asked herebull How much heat per mole of napthalene is released into t
he calorimeterTo do
bull Need to figure out how much heat is generated by the combustionbull Need to convert this total heat to q per mole (kJmol)
Practice Question
bull 1922g of methanol (CH3OH) was burned in a calorimeter The temp of water rose by 42 degrees celsius The heat capacity of the system (calorimeter plus water) is 104 kJcelsius Calculate the molar heat of the combustion of methanol
Calorimeter 2 - Constant-Pressure Calorimeter
bull Measures heat changes for non-combustible reaction (ie acid-base reactions)
bull Since the pressure remains the same change in enthalpy equals that to the change in heat
bull Also isolated and filled with water
Specific Heat will be used in calculations Waters specific heat is 4184 Jg(celsius)
Calorimetry - the measurement of heat changebull a calorimeter is an insulate
d closed container that creates an ISOLATED SYSTEM
bull a specific quantity of water surrounds a system carrying out a reaction
bull during the reaction heat leaves the system and is absorbed by the surrounding water
bull by recording temperature change the heat generated by a reaction can be recorded
Calorimetrybull Either heat capacity or specific heat must be a
pplied to find a substances change in heatbull Remember
heat capacity specific heat
(C) = m x (s)
tmsqtCq
cc
J
g
J g
bull Heat Capacity ndash heat needed to raise a certain quanity of a su
bstance 1 degree (celsius)
bull Specific Heat ndash the heat needed to raise a 1 gram of a specifi
c substance 1 degree (celsius)
Calorimeter 1 - Constant-Volume Calorimiter (The BOMB Calorimeter)
bull Purpose to collect data on combustible reactions
bull When adding heat to a substance in a Constant-Volume Calorimeters the pressure will increase because the volume has remained the same
bull The substance inside cannot expand
Calorimeter 1 - Constant-Volume Calorimiter (The BOMB Calorimeter)
bull Change of heat of a reaction is qrxn
bull Since the a calorimeter is an isolated system the change in heat of the calorimeter plus water is equal but opposite to the change of heat in the reaction
qsystem = qcal + qrxn = 0Meaning
qcal = -qrxn
Practice Questionbull A quantity of 1435 naphthalene (C10H8) is
burned in a calorimeter The water temp rises from 2028 to 2595 degrees celsius If the heat capacity (C) is 1017 kJcelsius calculate the molar heat combustion of C10
H8bull What is being asked herebull How much heat per mole of napthalene is released into t
he calorimeterTo do
bull Need to figure out how much heat is generated by the combustionbull Need to convert this total heat to q per mole (kJmol)
Practice Question
bull 1922g of methanol (CH3OH) was burned in a calorimeter The temp of water rose by 42 degrees celsius The heat capacity of the system (calorimeter plus water) is 104 kJcelsius Calculate the molar heat of the combustion of methanol
Calorimeter 2 - Constant-Pressure Calorimeter
bull Measures heat changes for non-combustible reaction (ie acid-base reactions)
bull Since the pressure remains the same change in enthalpy equals that to the change in heat
bull Also isolated and filled with water
Specific Heat will be used in calculations Waters specific heat is 4184 Jg(celsius)
Calorimetrybull Either heat capacity or specific heat must be a
pplied to find a substances change in heatbull Remember
heat capacity specific heat
(C) = m x (s)
tmsqtCq
cc
J
g
J g
bull Heat Capacity ndash heat needed to raise a certain quanity of a su
bstance 1 degree (celsius)
bull Specific Heat ndash the heat needed to raise a 1 gram of a specifi
c substance 1 degree (celsius)
Calorimeter 1 - Constant-Volume Calorimiter (The BOMB Calorimeter)
bull Purpose to collect data on combustible reactions
bull When adding heat to a substance in a Constant-Volume Calorimeters the pressure will increase because the volume has remained the same
bull The substance inside cannot expand
Calorimeter 1 - Constant-Volume Calorimiter (The BOMB Calorimeter)
bull Change of heat of a reaction is qrxn
bull Since the a calorimeter is an isolated system the change in heat of the calorimeter plus water is equal but opposite to the change of heat in the reaction
qsystem = qcal + qrxn = 0Meaning
qcal = -qrxn
Practice Questionbull A quantity of 1435 naphthalene (C10H8) is
burned in a calorimeter The water temp rises from 2028 to 2595 degrees celsius If the heat capacity (C) is 1017 kJcelsius calculate the molar heat combustion of C10
H8bull What is being asked herebull How much heat per mole of napthalene is released into t
he calorimeterTo do
bull Need to figure out how much heat is generated by the combustionbull Need to convert this total heat to q per mole (kJmol)
Practice Question
bull 1922g of methanol (CH3OH) was burned in a calorimeter The temp of water rose by 42 degrees celsius The heat capacity of the system (calorimeter plus water) is 104 kJcelsius Calculate the molar heat of the combustion of methanol
Calorimeter 2 - Constant-Pressure Calorimeter
bull Measures heat changes for non-combustible reaction (ie acid-base reactions)
bull Since the pressure remains the same change in enthalpy equals that to the change in heat
bull Also isolated and filled with water
Specific Heat will be used in calculations Waters specific heat is 4184 Jg(celsius)
bull Heat Capacity ndash heat needed to raise a certain quanity of a su
bstance 1 degree (celsius)
bull Specific Heat ndash the heat needed to raise a 1 gram of a specifi
c substance 1 degree (celsius)
Calorimeter 1 - Constant-Volume Calorimiter (The BOMB Calorimeter)
bull Purpose to collect data on combustible reactions
bull When adding heat to a substance in a Constant-Volume Calorimeters the pressure will increase because the volume has remained the same
bull The substance inside cannot expand
Calorimeter 1 - Constant-Volume Calorimiter (The BOMB Calorimeter)
bull Change of heat of a reaction is qrxn
bull Since the a calorimeter is an isolated system the change in heat of the calorimeter plus water is equal but opposite to the change of heat in the reaction
qsystem = qcal + qrxn = 0Meaning
qcal = -qrxn
Practice Questionbull A quantity of 1435 naphthalene (C10H8) is
burned in a calorimeter The water temp rises from 2028 to 2595 degrees celsius If the heat capacity (C) is 1017 kJcelsius calculate the molar heat combustion of C10
H8bull What is being asked herebull How much heat per mole of napthalene is released into t
he calorimeterTo do
bull Need to figure out how much heat is generated by the combustionbull Need to convert this total heat to q per mole (kJmol)
Practice Question
bull 1922g of methanol (CH3OH) was burned in a calorimeter The temp of water rose by 42 degrees celsius The heat capacity of the system (calorimeter plus water) is 104 kJcelsius Calculate the molar heat of the combustion of methanol
Calorimeter 2 - Constant-Pressure Calorimeter
bull Measures heat changes for non-combustible reaction (ie acid-base reactions)
bull Since the pressure remains the same change in enthalpy equals that to the change in heat
bull Also isolated and filled with water
Specific Heat will be used in calculations Waters specific heat is 4184 Jg(celsius)
Calorimeter 1 - Constant-Volume Calorimiter (The BOMB Calorimeter)
bull Purpose to collect data on combustible reactions
bull When adding heat to a substance in a Constant-Volume Calorimeters the pressure will increase because the volume has remained the same
bull The substance inside cannot expand
Calorimeter 1 - Constant-Volume Calorimiter (The BOMB Calorimeter)
bull Change of heat of a reaction is qrxn
bull Since the a calorimeter is an isolated system the change in heat of the calorimeter plus water is equal but opposite to the change of heat in the reaction
qsystem = qcal + qrxn = 0Meaning
qcal = -qrxn
Practice Questionbull A quantity of 1435 naphthalene (C10H8) is
burned in a calorimeter The water temp rises from 2028 to 2595 degrees celsius If the heat capacity (C) is 1017 kJcelsius calculate the molar heat combustion of C10
H8bull What is being asked herebull How much heat per mole of napthalene is released into t
he calorimeterTo do
bull Need to figure out how much heat is generated by the combustionbull Need to convert this total heat to q per mole (kJmol)
Practice Question
bull 1922g of methanol (CH3OH) was burned in a calorimeter The temp of water rose by 42 degrees celsius The heat capacity of the system (calorimeter plus water) is 104 kJcelsius Calculate the molar heat of the combustion of methanol
Calorimeter 2 - Constant-Pressure Calorimeter
bull Measures heat changes for non-combustible reaction (ie acid-base reactions)
bull Since the pressure remains the same change in enthalpy equals that to the change in heat
bull Also isolated and filled with water
Specific Heat will be used in calculations Waters specific heat is 4184 Jg(celsius)
Calorimeter 1 - Constant-Volume Calorimiter (The BOMB Calorimeter)
bull Change of heat of a reaction is qrxn
bull Since the a calorimeter is an isolated system the change in heat of the calorimeter plus water is equal but opposite to the change of heat in the reaction
qsystem = qcal + qrxn = 0Meaning
qcal = -qrxn
Practice Questionbull A quantity of 1435 naphthalene (C10H8) is
burned in a calorimeter The water temp rises from 2028 to 2595 degrees celsius If the heat capacity (C) is 1017 kJcelsius calculate the molar heat combustion of C10
H8bull What is being asked herebull How much heat per mole of napthalene is released into t
he calorimeterTo do
bull Need to figure out how much heat is generated by the combustionbull Need to convert this total heat to q per mole (kJmol)
Practice Question
bull 1922g of methanol (CH3OH) was burned in a calorimeter The temp of water rose by 42 degrees celsius The heat capacity of the system (calorimeter plus water) is 104 kJcelsius Calculate the molar heat of the combustion of methanol
Calorimeter 2 - Constant-Pressure Calorimeter
bull Measures heat changes for non-combustible reaction (ie acid-base reactions)
bull Since the pressure remains the same change in enthalpy equals that to the change in heat
bull Also isolated and filled with water
Specific Heat will be used in calculations Waters specific heat is 4184 Jg(celsius)
Practice Questionbull A quantity of 1435 naphthalene (C10H8) is
burned in a calorimeter The water temp rises from 2028 to 2595 degrees celsius If the heat capacity (C) is 1017 kJcelsius calculate the molar heat combustion of C10
H8bull What is being asked herebull How much heat per mole of napthalene is released into t
he calorimeterTo do
bull Need to figure out how much heat is generated by the combustionbull Need to convert this total heat to q per mole (kJmol)
Practice Question
bull 1922g of methanol (CH3OH) was burned in a calorimeter The temp of water rose by 42 degrees celsius The heat capacity of the system (calorimeter plus water) is 104 kJcelsius Calculate the molar heat of the combustion of methanol
Calorimeter 2 - Constant-Pressure Calorimeter
bull Measures heat changes for non-combustible reaction (ie acid-base reactions)
bull Since the pressure remains the same change in enthalpy equals that to the change in heat
bull Also isolated and filled with water
Specific Heat will be used in calculations Waters specific heat is 4184 Jg(celsius)
Practice Question
bull 1922g of methanol (CH3OH) was burned in a calorimeter The temp of water rose by 42 degrees celsius The heat capacity of the system (calorimeter plus water) is 104 kJcelsius Calculate the molar heat of the combustion of methanol
Calorimeter 2 - Constant-Pressure Calorimeter
bull Measures heat changes for non-combustible reaction (ie acid-base reactions)
bull Since the pressure remains the same change in enthalpy equals that to the change in heat
bull Also isolated and filled with water
Specific Heat will be used in calculations Waters specific heat is 4184 Jg(celsius)
Calorimeter 2 - Constant-Pressure Calorimeter
bull Measures heat changes for non-combustible reaction (ie acid-base reactions)
bull Since the pressure remains the same change in enthalpy equals that to the change in heat
bull Also isolated and filled with water
Specific Heat will be used in calculations Waters specific heat is 4184 Jg(celsius)