Solutions to Stoichiometry Homework Problem Set

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  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
      Name methane oxygen   carbon dioxide dihydrogen monoxide
      Balance 1 2   1 2
      MW (g mole-1) 16.0425 31.9988   44.0095 18.0153
      Given (g) 10.0 10.0      
      Given (mole) 0.623 0.312      
      Use (mole) 0.156 0.312      
      Produce (mole)       0.156 0.312
      Final (mole) 0.467 0   0.153 0.312
      Final (g) 7.49 0   6.86 5.62
      Total(g)         19.97
    4. C8H18 (l) + O2 (g) --> CO2 (g) + H2O (g)
        C8H18 O2 --> CO2 H2O
      Name octane oxygen   carbon dioxide dihydrogen monoxide
      Balance 2 25   16 18
      MW (g mole-1) 114.2285 31.9988   44.0095 18.0153
      Given (g) 10.0 10.0      
      Given (mole) 0.0875 0.312      
      Use (mole) 0.0250 0.312      
      Produce (mole)       0.200 0.225
      Final (mole) 0.0625 0   0.200 0.225
      Final (g) 7.14 0   8.80 4.05
      Total(g)         19.99
    5. NaCl (aq) + AgNO3 (aq) --> AgCl (s) + NaNO3 (aq)
        NaCl AgNO3 --> AgCl NaNO3
      Name sodium chloride silver (I) nitrate   silver (I) chloride sodium nitrate
      Balance 1 1   1 1
      MW (g mole-1) 58.4425 169.8734   143.3209 84.9947
      Given (g) 10.0 10.0      
      Given (mole) 0.171 0.0589      
      Use (mole) 0.0589 0.0589      
      Produce (mole)       0.0589 0.0589
      Final (mole) 0.112 0   0.0589 0.0589
      Final (g) 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
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