Stoichiometry

Stoichiometry

http://www.unit5.org/chemistry/Stoichiometry.html

Welcome to Mole Island

1 mole = 22.4 L @ STP

1 mol = molar mass

1 mol = 6.02 x 1023 particles

Stoichiometry Island Diagram

Mass

Particles

Volume Mole Mole

Mass

Known UnknownSubstance A Substance B


Volume

Particles

M

V

P

Mass Mountain

Liter Lagoon

Particle Place

Mole Island


Mass

Particles

Volume Mole Mole

Mass

Volume

Particles

Known Unknown

Substance A Substance B


1 mole = molar mass (g) Use coefficientsfrom balanced

chemical equation1 mole = 22.4 L @ STP

1 mole =

6.022 x

1023 partic

les

(atoms o

r molecu

les)

1 mole = 22.4 L @ STP

1 mole = 6.022 x 10 23 particles

(atoms or molecules)

1 mole =

molar m

ass (g

)

(gases) (gases)


Mass

Particles

Volume Mole Mole

Mass

Known UnknownSubstance A Substance B


Volume

Particles

M

V

P

Mass Mountain

Liter Lagoon

Particle Place

?

Visualizing a Chemical Reaction

Na + Cl2 NaCl

___ mole Cl2 ___ mole NaCl___ mole Na

2

10 5 10

2

10 5 10

___ mole NaCl10

Visualizing a Chemical Reaction

Na + Cl2 NaCl

___ mole Cl2___ mole Na

2

10 5

2

Proportional Relationships

I have 5 eggs. How many cookies can I make?

3/4 c. brown sugar1 tsp vanilla extract2 eggs2 c. chocolate chipsMakes 5 dozen cookies.

2 1/4 c. flour1 tsp. baking soda1 tsp. salt1 c. butter3/4 c. sugar

5 eggs 5 doz.

2 eggs= 12.5 dozen cookies

Ratio of eggs to cookies

Courtesy Christy Johannesson www.nisd.net/communicationsarts/pages/chem

150 cookies

Proportional Relationships

• StoichiometryStoichiometry– mass relationships between substances in a chemical

reaction– based on the mole ratio

• Mole RatioMole Ratio– indicated by coefficients in a balanced equation

2 Mg + O2 Mg + O22 2 MgO 2 MgO


Stoichiometry Steps1. Write a balanced equation.2. Identify known & unknown.3. Line up conversion factors.

– Mole ratio - moles moles– Molar mass - moles grams– Molarity - moles liters soln– Molar volume - moles liters gas

Core step in all stoichiometry problems!!

– Mole ratio - moles moles

4. Check answer.Courtesy Christy Johannesson www.nisd.net/communicationsarts/pages/chem

1 mol of a gas=22.4 Lat STP

Molar Volume at STP

Standard Temperature & Pressure0°C and 1 atm


Molar Volume at STP

Molar Mass(g/mol)

6.02 1023

particles/mol

MASSIN

GRAMSMOLES

NUMBEROF

PARTICLES

LITERSOF

SOLUTION

Molar Volume (22.4 L/mol)

LITERSOF GASAT STP

Molarity (mol/L)


How many moles of KClO3 must decompose in order to produce 9 moles of oxygen gas?

9 mol O2 2 mol KClO3

3 mol O2

= 6 mol KClO3

2KClO3 2KCl + 3O2 ? mol 9 mol


O2 KClO3

x mol KClO3 = 9 mol O2 = 6 mol KClO3

2 mol KClO3

3 mol O26 mol

How many grams of KClO3 are required to

produce 9.00 L of O2 at STP?

? g 9.00 L

Stoichiometry Problems

2KClO3 2KCl + 3O2


O2 KClO3

x g KClO3 = 9.00 L O2 22.4 L O2

= 32.8 g KClO3


3 mol O2

122.55 g KClO3

1 mol KClO3

32.8 g

How many grams of KClO3 are required to

produce 9.00 L of O2 at STP?

9.00 LO2

1 molO2

22.4 L O2

= 32.8 g KClO3

2 molKClO3

3 molO2

122.55g KClO3

1 molKClO3

? g 9.00 L2KClO3 2KCl + 3O2


O2 KClO3

x g KClO3 = 9.00 L O2 22.4 L O2

= 32.8 g KClO3


3 mol O2

122.55 g KClO3

1 mol KClO3

32.8 g

How many grams of silver will be formed from 12.0 g copper?

12.0g Cu

1 molCu

63.55g Cu

= 40.7 g Ag

Cu + 2 AgNO3 2 Ag + Cu(NO3)2

2 molAg

1 molCu

107.87g Ag

1 molAg

12.0 g ? g


Cu Ag

x g Ag = 12.0 g Cu63.55 g Cu

= 40.7 g Ag1 mol Cu 2 mol Ag

1 mol Cu107.87 g Ag

1 mol Ag40.7 g

2 Na + Cl2 2 NaCl2 grams 1 gram 2 grams W R O N G

Violates Law of Conservation of Matter

2 atoms 1 molecule 2 molecules*

*Better name would be “formula unit”

2 moles 1 mole 2 moles

100 g x L x g

Na Cl2

x L Cl2 = 100 g Na23 g Na

= 49 L Cl21 mol Na 1 mol Cl2

2 mol Na22.4 L Cl21 mol Cl2

48.69 L

Right side of room…calculate how many grams of NaCl will be produced from 100 g of Na.

Left side of room…calculate how many grams of NaCl will be produced from 48.69 L of Cl2.

Na NaCl

x g NaCl = 100 g Na23 g Na

= 254 g NaCl1 mol Na 2 mol NaCl

2 mol Na58.5 g NaCl1 mol NaCl

Cl2 NaCl

x g NaCl = 48.69 L Cl2 22.4 L Cl2= 254 g NaCl

1 mol Cl2 2 mol NaCl1 mol Cl2

58.5 g NaCl1 mol NaCl

Stoichiometry

KClO3 KCl + O232 2500 g x g x L

KClO3 O2

x L O2 = 500 g KClO3 122.5 g KClO3

= 137 L O2

1 mol KClO3 3 mol O2

2 mol KClO3

22.4 L O2

1 mol O2

KClO3 KCl

x g KCl = 500 g KClO3 122.5 g KClO3

= 304 g KCl1 mol KClO3 2 mol KCl

2 mol KClO3

74.5 g KCl1 mol KCl

(304 g)

(196 g)

x g O2 = 137 L O2 22.4 L O2

= 196 g O2

1 mol O2 32 g O2

1 mol O2

137 L

Stoichiometry

2 TiO2 + 4 Cl2 + 3 C CO2 + 2 CO + 2 TiCl4

4.55 molx mol

C Cl2

x mol Cl2 = 4.55 mol C3 mol C

= 6.07 mol C4 mol Cl2

C TiO2

x molecules TiCl4 = 115 g TiO2 80 g TiO2

= 8.66x1023 molecules TiCl4

1 mol TiO2 2 mol TiCl42 mol TiO2

6.02x1023 molecules TiCl41 mol TiCl4

x g TiO2 = 4.55 mol C3 mol C

= 243 g TiO2

2 mol TiO2 80 g TiO2

1 mol TiO2

How many moles of chlorine will react with 4.55 moles of carbon?

How many grams of titanium (IV) oxide will react with 4.55 moles of carbon?

x g

How many molecules of TiCl4 will react with 115 g TiO2?

TiO2 TiCl4

x molecules115 g

6.02x1023 atoms H2O6.02x1023 molecules H2O

Which has more atoms: 30 g aluminum metal or 18 mL distilled water?

x atoms Al = 30 g Al27 g Al

= 6.69x1023 atoms Al1 mol Al 6.02x1023 atoms Al

1 mol Al

How many atoms of aluminum are in 30 g of aluminum?

Al

x atoms Al = 30 g Al27 g Al

= 6.69x1023 atoms Al6.02x1023 atoms Al

Al

x atoms = 18 mL H2O 1000 mL H2O

= 1.45x1021 atoms

1 L H2O 1 mol H2O22.4 L H2O

How many atoms are in 18 mL of water? H2O

x atoms = 18 mL H2O 1 mL H2O

= 1.81x1024 atoms

1 g H2O 1 mol H2O 18 g H2O

How many atoms are in 18 mL of water?

1 mol H2O3 atoms

1 molecule H2O

1 moL H2O6.02x1023 molecules H2O 3 atoms

1 molecule H2O

W R O N GW R O N G

Recall, density of water

LITERS is ONLY used for GASES @ STPLITERS is ONLY used for GASES @ STP

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Stoichiometry