# Solutions to Stoichiometry Homework Problem Set

This problem set was developed by S.E. Van Bramer for Chemistry 145 at Widener University.

1. Balance the following equations. Given 10.0 grams of each reactant. How many grams of each product could be produced? What is the total mass of reactants and products when the reaction is complete?

1. LiOH (s) + H2SO4 (aq) --> H2O (l) + Li2SO4 (aq)

 LiOH H2SO4 --> H2O Li2SO4 Name lithium hydroxide sulfuric acid dihydrogen monoxide lithium sulfate Balance 2 1 2 1 MW (g mol-1) 23.948 98.079 18.0153 109.946 Given (g) 10.0 10.0 Given (mole) 0.418 0.102 Use (mole) 0.204 0.102 Produce (mole) 0.204 0.104 Final (mole) 0.214 0 0.204 0.104 Final (g) 5.12 0 3.68 11.4 Total(g) 20.2

2. Mg(OH)2 (aq) + H3PO4 (l) --> Mg3(PO4)2 (aq) + H2O (l)
 Mg(OH)2 H3PO4 --> Mg3(PO4)2 H2O Name magnesium hydroxide phosphoric acid magnesium phosphate dihydrogen monoxide Balance 3 2 1 6 MW (g mol-1) 58.3197 97.9925 262.8577 18.0153 Given (g) 10.0 10.0 Given (mole) 0.171 0.102 Use (mole) 0.153 0.102 Produce (mole) 0.051 0.306 Final (mole) 0.018 0 0.051 0.306 Final (g) 1.05 0 13.4 5.51 Total(g) 19.96

3. CH4 (g) + O2 (g) --> CO2 (g) + H2O (g)
CH4 O2 --> CO2 H2O Balance Name methane oxygen carbon dioxide dihydrogen monoxide 1 2 1 2 16.0425 31.9988 44.0095 18.0153 10.0 10.0 0.623 0.312 0.156 0.312 0.156 0.312 0.467 0 0.153 0.312 7.49 0 6.86 5.62 Total(g) 19.97

4. C8H18 (l) + O2 (g) --> CO2 (g) + H2O (g)
C8H18 O2 --> CO2 H2O Balance Name octane oxygen carbon dioxide dihydrogen monoxide 2 25 16 18 114.2285 31.9988 44.0095 18.0153 10.0 10.0 0.0875 0.312 0.0250 0.312 0.200 0.225 0.0625 0 0.200 0.225 7.14 0 8.80 4.05 Total(g) 19.99

5. NaCl (aq) + AgNO3 (aq) --> AgCl (s) + NaNO3 (aq)
NaCl AgNO3 --> AgCl NaNO3 Balance Name sodium chloride silver (I) nitrate silver (I) chloride sodium nitrate 1 1 1 1 58.4425 169.8734 143.3209 84.9947 10.0 10.0 0.171 0.0589 0.0589 0.0589 0.0589 0.0589 0.112 0 0.0589 0.0589 6.56 0 8.44 5.01 Total(g) 20.01

6. CH3COOH (aq) + NaHCO3 (s) --> CO2 (g) + H2O (l) + NaCH3COO (aq)
CH3COOH NaHCO3 --> CO2 H2O NaCH3COO
Name acetic acid sodium hydrogen carbonate carbon dioxide dihydrogen monoxide sodium acetate
Balance 1 1   1 1 1
MW (g mole-1) 60.0520 84.1166   44.0095 18.0153 82.0304
Given (g) 10.0 10.0
Given (mole) 0.166 0.119
Use (mole) 0.119 0.119
Produce (mole)       0.119 0.119 0.119
Final (mole) 0.047 0   0.119 0.119 0.119
Final (g) 2.8 0   5.24 2.14 9.76
Total(g)     19.94

2. Balance the following equations. Starting with 25.0 grams of each reactant, how many grams of each product could be produced? What is the total mass of reactants and products when the reaction is complete?

1. Nitrogen monoxide reacts with ozone (trioxide) to produce nitrogen dioxide and oxygen molecules.

NO + O3 --> NO2 + O2
 NO O3 --> NO2 O2 Balance 1 1 1 1 MW (g mole-1) 30.0061 47.9982 46.0055 31.9988 Given (g) 25.0 25.0 Given (mole) 0.833 0.521 Use (mole) 0.521 0.521 Produce (mole) 0.521 0.521 Final (mole) 0.312 0 0.521 0.521 Final (g) 9.37 0 24.0 16.7 Total(g) 50.07

2. Iron (III) oxide reacts with zinc metal to produce iron metal and zinc (II) oxide.

Fe2O3 + Zn --> Fe + ZnO
 Fe2O3 Zn --> Fe ZnO Balance 1 3 2 3 MW (g mole-1) 159.692 65.39 55.847 81.39 Given (g) 25.0 25.0 Given (mole) 0.156 0.382 Use (mole) 0.127 0.382 Produce (mole) 0.255 0.382 Final (mole) 0.029 0 0.255 0.382 Final (g) 4.6 0 14.2 31.1 Total(g) 49.9

3. Hydrobromic acid reacts with aluminum metal to produce hydrogen gas and aluminum bromide.

HBr + Al --> H2 + AlBr3
 HBr Al --> H2 AlBr3 Balance 6 2 3 2 MW (g mole-1) 80.912 26.981539 2.01948 266.694 Given (g) 25.0 25.0 Given (mole) 0.309 0.926 Use (mole) 0.309 0.103 Produce (mole) 0.154 0.103 Final (mole) 0 0.823 0.154 0.103 Final (g) 0 22.2 0.311 27.5 Total(g) 50.01