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Agenda: 4/23 or 4/24
• Purpose: To use mathematical formulas to predict how a gas will change
• Warm-up: States of Matter• Kinetic Molecular Theory• Measurements used in Gas
GASESUnit 8
Essential Standards: 2.1.5
Chapters 13 & 14
Purpose: To use mathematical formulas to predict how a gas will change
GAS LAWS (FORMULAS)
-Gas molecules act in orderly and predictable ways.
- We can use mathematical formulas to predict what they will do when we change Temperature,
Pressure, or Amount.
Warm-up: What are gases? Describe the location & movement of the particles at each state of matter?
How are gases different?
What are gases? How are they different?Describe the gases in terms of size and type of compound (bond type).
Elements that exist as gases at 250C and 1 atmosphere
Differentiating gases from solids and liquids
• Kinetic Molecular Theory• or “Why solids, liquids and gases behave as they do”
• How are gases different?
Differentiating gases from solids and liquids• Kinetic Molecular Theory
• or “Why solids, liquids and gases behave as they do”
• All matter is made of __________________and these are always in _________________. - Temperature determines the ____________of the ___________________.There are 3 states of matter on earth: _______,________________, __________________.
• DiscoveryEd video: Kinetic Molecular Theory• Kinetic_Molecular_Theory.wmv
• Animation – • http://
www.pbs.org/wgbh/nova/physics/states-of-matter.html• Includes Temperature & Pressure; Water, Carbon dioxide
and hydrogen gas
Gas Behavior – Kinetic Molecular Theory
• http://ed.ted.com/lessons/describing-the-invisible-properties-of-gas-brian-bennett
• 5 characteristics of gases
1. -
2. -
3. -
4. -
5. -
Chemical particles (atoms, molecules, or compounds) act differently when they are in different states of matter
PHET – States of Matter – Basicshttps://phet.colorado.edu/en/simulation/states-of-matter-basics
animationsHeating curveKMT- SolidKMT-Liquid KMT- Gas
Ways we measure gases:
Abbreviation Measurement
Volume
Temperature
Number or quantity – atoms or molecules
Pressure
Gas Temperature: Always use Kelvin
Celcius Kelvin
Temperature Conversions
• Convert 25.0℃ to Kelvin
• Convert 375K to ℃
• Convert -50℃ to K
Pressure • http://www.dlt.ncssm.edu/Tiger/chem3.htm
AnimationAtmospheric pressure
You Tube – Atmospheric Pressure
Sea level 1 atm
4 miles 0.5 atm
10 miles 0.2 atm
Air Pressure of the Atmosphere
Units of Pressure
1 atm = 760 mmHg = 760 torr
1 atm = 101 kPa (101,325 Pa)
Barometer
Pressure = ForceArea
Or 760 mm of Mercury
Measuring Pressure: UnitsUnit Unit name STP:
Measurement at sea level & 0°C
Mm Hg Mm Mercury 760 mm Hg
Atm atomospheres 1 atm
kPa kiloPascals 101 kPa
Torr Torr 760 torr
PSI*Tire pressure
Pounds per square inch
14.7 psi
STP = Standard Temperature & PressureWhat does the chemistry reference table tell you? • STP= 1 atm at 0°C or _________ K• = __________mm Hg• = __________ KPa• = __________ torr
Standard Molar Volume of a Gas: 1 mole = ______ Liter(volume occupied by one mole of any gasat STP = ______ Liter)
Pressure Conversions
• Convert 98.35 kPa to atm
• Convert 745 mm Hg to atm
• Convert 740 mm Hg to kPa
GAS LAWSShows the relationship of volume. Temperature, pressure and quantity of molecules in mathematical terms
Gases act in predictable ways so we can use
mathematical formulas to determine how they act
http://phet.colorado.edu/en/simulation/gas-properties
Three Major Laws
Combined Gas Law
P₁V₁= P₂V₂ T₁ T₂
Ideal Gas Law
PV = nRT
•Dalton’s Law of Partial Pressure
Ptotal = P₁+P₂+P₃+Petc.
“A Rational Equation” means an equation which uses ________.
Isolating the Unknown Variable
P₁V₁ = P₂V₂ T₁ T₂
We can slide diagonally across the equal sign without changing the mathematical relationship.
Need variable cards
Isolating the Unknown Variable
P₁V₁ = P₂V₂ T₁ T₂
We can slide diagonally across the equal sign without changing the mathematical relationship.
Isolating the Unknown Variable
P₁V₁ = P₂V₂ T₁ T₂
We can slide diagonally across the equal sign without changing the mathematical relationship.
Isolating the Unknown Variable
P₁V₁ = P₂V₂ T₁ T₂
We can slide diagonally across the equal sign without changing the mathematical relationship.
Combined Gas Law
Combined Gas Law
Initial condition(1) Final condition (2)
Pressure
Volume
Temp. K
P₁V₁ = P₂V₂ T₁ T₂
Combined Gas Law: Example
Initial condition(1) Final condition (2)
Pressure
Volume
Temp. K
P₁V₁ = P₂V₂ T₁ T₂
A gas at 110 kPa and 30℃ fills a flexible container with an initial volumeOf 2.00L. If the temperature is raised to 80℃ and the pressure increasedTo 440 kPa, what is the new volume?
Answer: 0.58L
Constant variable Changing variables Law
Temperature Boyles
Pressure Charles
Volume Gay-Lussac
Combined Gas Law P₁V₁= P₂V₂ T₁ T₂
Keeping one variable constant:
Boyles’ Law Animation• http://www.chem.iastate.edu/group/Greenbowe/sections/
projectfolder/flashfiles/gaslaw/boyles_law_graph.html
Boyles’ Law: Vary P & VUses: bicycle pump; syringe for injections; popping a balloon by squeezing; Scuba diving: increase in bubble size as rise to surface of water Others?
Initial condition(1) Final condition (2)
Pressure
Volume
Temp. K
P₁V₁ = P₂V₂ T₁ T₂
http://phet.colorado.edu/en/simulation/gas-properties
Boyles’ Law: ExampleA cylinder of oxygen has a volume of 2.0L. The pressure of the gas is 10 atm at 0℃. What will be the volume at STP?
Initial condition(1) Final condition (2)
Pressure
Volume
Temp. K
P₁V₁ = P₂V₂ T₁ T₂
Boyles’ Law: Practice Problems
Initial condition(1) Final condition (2)
Pressure
Volume
Temp. K
P₁V₁ = P₂V₂ T₁ T₂
Boyles’ Law: Practice Problems
Initial condition(1) Final condition (2)
Pressure
Volume
Temp. K
P₁V₁ = P₂V₂ T₁ T₂
Charles’ Law: Vary V & TUses: Hot Air Balloons
Decorating with party balloons; Cooked turkey monitor/device; Playing basketball on a cold day
Initial condition(1) Final condition (2)
Pressure
Volume
Temp. K
P₁V₁ = P₂V₂ T₁ T₂
Charles’ Law: Practice Problems
Initial condition(1) Final condition (2)
Pressure
Volume
Temp. K
P₁V₁ = P₂V₂ T₁ T₂
Charles’ Law: Practice Problems
Initial condition(1) Final condition (2)
Pressure
Volume
Temp. K
P₁V₁ = P₂V₂ T₁ T₂
Gay Lusaac’s Law: Vary P and TUses: Heating cans (soup, spray); Pop corn;
Initial condition(1) Final condition (2)
Pressure
Volume
Temp. K
P₁V₁ = P₂V₂ T₁ T₂
http://phet.colorado.edu/en/simulation/gas-properties
Gay Lussac’s Law: Practice Problems
Initial condition(1) Final condition (2)
Pressure
Volume
Temp. K
P₁V₁ = P₂V₂ T₁ T₂
Gay Lussac’s Law: Practice Problems
Initial condition(1) Final condition (2)
Pressure
Volume
Temp. K
P₁V₁ = P₂V₂ T₁ T₂
COMBINED GAS LAW
Combined Gas Law
Initial condition(1) Final condition (2)
Pressure
Volume
Temp. K
P₁V₁ = P₂V₂ T₁ T₂
A balloon is partially filled with helium on the ground in the mountains (temp.is 22°C and the pressure is 740 torr. At these conditions, the volume is 10 m³.If released, what would be the volume in m³ at an altitude 5300 m where the pressure is 370 torr and the temperature is - 23°C?
Combined Gas Law
Initial condition(1) Final condition (2)
Pressure
Volume
Temp. K
P₁V₁ = P₂V₂ T₁ T₂
The volume of a gas is 27.5 mL at 22°C and 0.974 atm. What will the volume be at 15°C and 0.993 atm?
Combined Gas Law
Initial condition(1) Final condition (2)
Pressure
Volume
Temp. K
P₁V₁ = P₂V₂ T₁ T₂
A 700 mL gas sample at STP is compressed to a volumeof 200mL and the temperature is increased to 30°C. What is the new pressure of the gas?
P₁ V₁ T₁ P₂ V₂ T₂
1.5 atm 3.0L 20°C 2.5 atm ? 30°C
Combined Gas Law
Ideal Gas LawUse when________ is included.
• Formula: PV = nRT
P =
V=
n=
R= 0.0821 L∙atm
mol∙K
T=
Ideal Gas Law• Formula: PV = nRTWhat is the pressure exerted by a 0.5 mol sample of N₂ gas in a 10L container at 278K?
P = V= n= R= 0.0821 L∙atm mol∙KT=
Ideal Gas Law
• Formula: PV = nRTHow many moles of O₂ will occupy a volume of 2.5L at 1.2 atm and 25°C?
P = V= n= R= 0.0821 L∙atm mol∙KT=
Ideal Gas Law: PV = nRTWhat volume will 2 mol of N₂ gas occupy at 720 torr and 20°C?
P = V= n= R= 0.0821 L∙atm mol∙KT=
Ideal Gas Law: PV = nRTAt what temperature will 5 grams of Cl₂ gas exert with a pressure of 900 mm Hg and volume of 750 mL?
P = V= n= R= 0.0821 L∙atm mol∙KT=
Dalton’s Law of Partial Pressure
• Mixture of gases (no reaction takes place)
• What is the total blood gas pressure for a person having CO₂ partial pressure of 60.1 mm Hg and an O₂ partial pressure of 39.2 mm Hg?
Ptotal = P₁+P₂+P₃+Petc.
Dalton’s Law of Partial Pressures
V and T are
constant
P1 P2 Ptotal = P1 + P2
Avogadro’s Law
V a number of moles (n)
V = constant x n
V1/n1 = V2/n2
Constant temperatureConstant pressure