Culver City H.S. • Chemistry Honors

12 · Stoichiometry

STATION 1 • CHEMICAL REACTIONS 1

For each of the following equations, classify the reaction, then balance the equation.

C—combustion / DR—double replacement / SR—single replacement / S—synthesis / D—decomposition

___ … ZnS (aq) + … HCl (aq) " …ZnCl2 (aq) + …H2S (g)

___ … HCl (aq) + … Zn (s) " … ZnCl2 (aq) + … H2 (g)

___ … H2 (g) + … O2 (g) " … H2O (ℓ)

___ … Ca(OH)2 (aq) + … H3PO4 (aq) " …Ca3(PO4)2 (s) + … H2O (ℓ)

12 · Stoichiometry

STATION 2 • CHEMICAL REACTIONS 2

For each of the following equations, classify the reaction, then balance the equation.

C—combustion / DR—double replacement / SR—single replacement / S—synthesis / D—decomposition

___ … Al (s) + … Fe3O4 (s) " … Al2O3 (s) + … Fe (s)

___ … C5H12 (ℓ) + …O2 (g) " … CO2 (g) + … H2O (ℓ)

___ … H2O2 (aq) " … H2O (ℓ) + … O2 (g)

___ … CaO (s) + … CO2 (g) " … CaCO3 (s)


12 · Stoichiometry

STATION 3 • STOICHIOMETRY INTRO

Chewy Sugar Cookies (makes 76 cookies)

5 cups flour 2 cups unsalted butter 3 teaspoons baking powder

2 cups sugar 1 teaspoon kosher salt 4 large eggs 2 teaspoon vanilla extract

·  How many eggs are required to make 114 cookies?

·  How many cookies could be made with 3.5 cups of sugar?

·  How many teaspoons of vanilla extract is needed if 5 teaspoons of baking powder are used?

12 · Stoichiometry

STATION 4 • MOLE RATIOS

1. Consider the following balanced equation: 2 CH3OH(l) + 3 O2(g) " 2 CO2(g) + 4 H2O(g)

a. How many moles of water form if 4.3 moles of CH3OH react?

b. How many moles of oxygen gas are needed to react with 0.40 moles CH3OH?

2. Given that 0.25 moles of X react with 0.33 moles of Y to produce 0.50 moles of Z, give the balanced equation:

_____ X + _____ Y à _____ Z

12 · Stoichiometry

STATION 5 • STOICHIOMETRY PROBLEM 1

Consider the following balanced equation: C3H8(g) + 5 O2(g) " 3 CO2(g) + 4 H2O(g)

Molar Masses: 44.11 32.00 44.01 18.02 g/mol

1. What mass of CO2 is formed when 100. grams of C3H8 react?

2. What volume (at STP) of O2(g) is needed to completely react with 7.55 grams of C3H8?

12 · Stoichiometry

STATION 6 • LIMITING & EXCESS REACTANTS

For the following reactions, identify the limiting and the excess reactant. Give reasons from your choices.

1.  wood burning in a campfire.

2.  sulfur in air reacting with silver flatware to produce tarnish, or silver sulfide.

3.  baking powder in cake batter decomposing to produce carbon dioxide, which makes the cake rise.

12 · Stoichiometry

STATION 7 • STOICHIOMETRY PROBLEM 2

Consider the following balanced equation: 3 Mg (s) + Al2(SO4)3 (aq) " 2 Al (s) + 3 MgSO4 (aq)

Molar Masses: 24.31 342.17 26.98 120.38 g/mol

1. If 100.0 kg of Mg react with 200.0 kg of Al2(SO4)3, which reactant is limiting?

2. How much excess reactant remains unused?

3. What is the theoretical yield of aluminum?

4. If 25.0 kilograms of aluminum are formed, what is the percent yield of aluminum?

12 · Stoichiometry

STATION 8 • MOLAR VOLUME OF H2 LAB

Given the data below, calculate the molar volume of H2 gas produced in the experiment.

Length of Mg ribbon used / 2.50 cm
Mass of one meter of Mg ribbon / 1.44 g
Volume of gas collected / 36.7 mL
Room temperature and pressure / 22°C, 761 mmHg

Moles of H2 gas formed = ______

Volume of H2 gas collected = ______

Molar Volume of H2 gas = ______