Mole Stoichiometry



Name: ________________________

Hour: ____ Date: ___________

Chemistry: Molarity and Stoichiometry

Using the definition of molarity, the given balanced equations, and stoichiometry, solve the following problems.

1. Ca(OH)2(aq) + H2SO4(aq) ( CaSO4(s) + 2H2O(l)

a. How many L of 0.5 M Ca(OH)2(aq) are needed in order to have 5.5 mol of Ca(OH)2?

b. Find the number of mol of H2SO4 needed to react with 5.5 mol of Ca(OH)2.

c. If the H2SO4(aq) is 0.82 M, how many L of it are needed to react with 5.5 mol of Ca(OH)2?

2. CaCO3(aq) + 2HCl(aq) ( CO2(g) + CaCl2(aq) + H2O(l)

a. How many g of CaCO3(s) are needed to make 1.2 L of 1.7 M CaCO3(aq) solution?

b. How many L of 3 M HCl(aq) are needed to completely react with this amount of CaCO3?

c. How many mol of H2O(l) will be produced?

3. 2NH4Cl(aq) + Ca(OH)2(aq) ( CaCl2(aq) + 2NH3(g) + 2H2O(l)

a. How many g of NH4Cl(s) are needed to make 1 L of a 2 M solution of NH4Cl(aq)?

b. How many g of Ca(OH)2(s) are needed to make 1 L of a 1 M solution of Ca(OH)2(aq)?

c. How many g of CaCl2 will be formed from this reaction?

4. Zn(s) + 2HCl(aq) ( ZnCl2(aq) + H2(g)

a. How many L of 0.1 M HCl(aq) react with 26 g Zn(s)?

b. How many g of Zn(s) are needed to react with 2 L of 0.25 M HCl(aq)?

c. If you start with 45 g HCl, how many L of H2(g) will you make (at STP)?

Answers: 1a. 11 L of 0.5 M Ca(OH)2(aq) 3a. 107 g NH4Cl(s)

1b. 5.5 mol H2SO4 3b. 74.1 g Ca(OH)2(s)

1c. 6.71 L of 0.82 M H2SO4(aq) 3c. 111.1 g CaCl2

2a. 204 g CaCO3(s) 4a. 7.95 L of 0.1 M HCl(aq)

2b. 1.36 L of 3 M HCl 4b. 16.4 g Zn(s)

2c. 2.04 mol H2O(l) 4c. 13.8 L H2 (at STP)

KEY

Chemistry: Molarity and Stoichiometry

Using the definition of molarity, the given balanced equations, and stoichiometry, solve the following problems.

1. Ca(OH)2(aq) + H2SO4(aq) ( CaSO4(s) + 2H2O(l)

a. How many L of 0.5 M Ca(OH)2(aq) are needed in order to have 5.5 mol of Ca(OH)2?

M = mol /L

L = mol / M

L = 5.5 mol Ca(OH) 2 / 0.5 M Ca(OH) 2

L = 11 L Ca(OH) 2

b. Find the number of mol of H2SO4 needed to react with 5.5 mol of Ca(OH)2.

x mol H2SO4 = 5.5 mol Ca(OH) 2 x (1 mol H2SO4) = 5.5 mol H2SO4

(1 mol Ca(OH) 2)

c. If the H2SO4(aq) is 0.82 M, how many L of it are needed to react with 5.5 mol of Ca(OH)2?

M = mol / L

L = mol / M

L = 5.5 mol H2SO4 / 0.82 M H2SO4

L = 6.7 liters H2SO4

2. CaCO3(aq) + 2HCl(aq) ( CO2(g) + CaCl2(aq) + H2O(l)

a. How many g of CaCO3(s) are needed to make 1.2 L of 1.7 M CaCO3(aq) solution?

M = mol / L

x g Ca = 2.04 mol CaCO3 x (100.1 g CaCO3)

mol = M x L (1 mol CaCO3)

mol = (1.7 M CaCO3) x (1.2 L CaCO3) x = 204.2 g CaCO3

mol = 2.04 mol CaCO3

b. How many L of 3 M HCl(aq) are needed to completely react with this amount of CaCO3?

M = mol / L

X mol HCl = 2.04 mol CaCO3 x (2 mol HCl) = 4.08 mol HCl

(1 mol CaCO3) L = mol / M

L = 4.08 mol HCl / 3 M HCl

L = 1.36 L HCl

c. How many mol of H2O(l) will be produced?

X mol H2O = 2.04 mol CaCO3 x (1 mol H2O) = 2.04 mol H2O

(1 mol CaCO3)

3. 2NH4Cl(aq) + Ca(OH)2(aq) ( CaCl2(aq) + 2NH3(g) + 2H2O(l)

a. How many g of NH4Cl(s) are needed to make 1 L of a 2 M solution of NH4Cl(aq)?

b. How many g of Ca(OH)2(s) are needed to make 1 L of a 1 M solution of Ca(OH)2(aq)?

c. How many g of CaCl2 will be formed from this reaction?

5. Zn(s) + 2HCl(aq) ( ZnCl2(aq) + H2(g)

a. How many L of 0.1 M HCl(aq) react with 26 g Zn(s)?

b. How many g of Zn(s) are needed to react with 2 L of 0.25 M HCl(aq)?

c. If you start with 45 g HCl, how many L of H2(g) will you make (at STP)?

Answers: 1a. 11 L of 0.5 M Ca(OH)2(aq) 3a. 107 g NH4Cl(s)

1b. 5.5 mol H2SO4 3b. 74.1 g Ca(OH)2(s)

1c. 6.71 L of 0.82 M H2SO4(aq) 3c. 111.1 g CaCl2

2a. 204 g CaCO3(s) 4a. 7.95 L of 0.1 M HCl(aq)

2b. 1.36 L of 3 M HCl 4b. 16.4 g Zn(s)

2c. 2.04 mol H2O(l) 4c. 13.8 L H2 (at STP)

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