Name: ______ANSWER KEY______Date: ______Period: ______

An Introduction to Stoichiometry

  1. 2C2H6 + 7 O2→ 4CO2 + 6H2O
  1. What is the mole ratio: 2C2H6 : 7O2:4CO2 : 6H2O
  1. How many moles of oxygen are required to react with 2 moles of ethane, C2H6 ?

2 moles C2H6 x 7 mol O2 = 7 mol O2

2 mol C2H6

  1. How many moles of oxygen are required to react with 2.40 moles of ethane?

2.40 moles C2H6 x 7 mol O2 = 8.40 mol O2

2molC2H6

  1. Calculate the number of grams of oxygen required to react with 150 grams of ethane.

150 grams C2H6 x 1 mol C2H6 x 7 mol O2 x 32 g O2 = 559 560 g O2

30.0694 g C2H6 2 mol C2H6 1 mol O2

  1. N2 + 3H2→ 2NH3
  1. What is the mole ratio: 1N2 : 3 H2:2 NH3
  1. How many moles of hydrogen are required to produce 4.20 moles of ammonia, NH3?

4.20 mol NH3 x 3 mol H2 = 6.3 mol H2

2 mol NH3

  1. How many grams of hydrogen gas are required to produce 88 grams of ammonia?

88 g NH3 x 1 mol NH3 x 3 mol H2 x 2.016 g H2 = 16 g H2

17.0307g NH3 2 mol NH3 1 mol H2

  1. C7H16 + 11O2→ 7CO2 + 8H2O
  1. How many grams of oxygen are required to react with 3.5 moles of heptane, C7H16 ?

3.5 mol C7H16 x 11 mol O2 x 32 g O2 = 1232  1200 g O2

1 mol C7H16 1 mol O2

  1. How many grams of carbon dioxide will be produced by the combustion of 66.0 grams of heptane?

66.0 g C7H16 x 1 mol C7H16 x 7 mol CO2 x 44.011g CO2 = 203g CO2

100.205g C7H16 1 mol C7H16 1 mol CO2

  1. 4NH3 + 5O2 → 4NO + 6H2O
  1. How many moles of ammonia will react with 49.6 moles of oxygen?

49.6 moles O2 x 4 mol NH3 = 39.7 mol NH3

5 mol O2

  1. If 37.8 moles of ammonia react, how many grams of water will be produced?

37.8 mol NH3 x 6 mol H2O x 18.016g H2O = 1021.5  1020g H2O

4 mol NH3 1 mol NH3

  1. Zn + 2HCl → H2 + ZnCl2

How many molecules of zinc (II) chloride are produced from 42.7 grams of zinc?

42.7g Zn x 1 mol Zn x 1 mol ZnCl2 x 6.02x1023 molecules ZnCl2 = 3.93 x 1023ZnCl2

65.39g Zn 1 mol Zn 1 mol ZnCl2

  1. 2SO2 + O2 → 2SO3

How many grams of oxygen gas are required to produce 18.6 g of sulfur trioxide?

18.6g SO3 x 1 mol SO3 x 1 mol O2 x 32 g O2 = 3.72 g O2

80.065g SO3 2 mol SO3 1 mol O2

More Stoich Practice:

Aqueous hydrochloric acid reacts with aqueous zinc (II) sulfide to produce an aqueous ionic compound and gaseous dihydrogen sulfide. (zinc will retain its charge in the product)

  1. Write a Balanced the equation: (using correct formulas and the states of each compound)

2 HCl(aq) + ZnS(aq)  ZnCl2(aq) + H2S(g)

  1. Identify the type of reaction.Double displacement
  1. Why is ZnClan incorrect formula for the aqueous ionic compound? The charge on Zn is +2
  1. What is the name for the aqueous ionic compound?Zinc (II) chloride
  1. What are the mole ratios for this reaction? 2 HCl : 1 ZnS : 1 ZnCl2 : 1 H2S
  1. How many moles of zinc (II) sulfide are needed to react with 1.58 moles of hydrochloric acid? (show your work)

1.58 mol HCl x 1 mol ZnS = 0.790 mol ZnS

2 mol HCl

  1. How many grams of aqueous ionic compoundare produced from 1.58 moles of hydrochloric acid? (show your work)

1.58 mol HCl x 1 mol ZnCl2 x 136.296g ZnCl2 =108 g ZnCl2

2 mol HCl 1 mol ZnCl2

  1. How many molecules of hydrochloric acid are required to produce 3.01 grams of aqueous ionic compound? (show your work)

3.01g ZnCl2 x 1 mol ZnCl2 x 2 mol HCl x 6.02x1023 molecules HCl = 2.66 x 1022

136.296g ZnCl2 1 mol ZnCl2 1 mol HClmolecules HCl