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Homework Help: Determining Limiting Reactants

  1. Sep 20, 2008 #1
    1. The problem statement, all variables and given/known data
    The reaction of calcium hydride and water produces calcium hydroxide and hydrogen as products. How many moles of H2 gas will be formed in the reaction between 0.80 mol CaH2 solid and 1.29 mol H2O liquid? (Two Significant Digits):

    2. Relevant equations

    3. The attempt at a solution
    Well the balanced equation for this reaction I believe is CaH2 + 2H2O -> Ca(OH)2 + H2. Therefore the molar ration is about 2:1 so if 1.29 mol is reacts than 0.645 will be formed? But I'm always wrong? Any help is appreciated.
  2. jcsd
  3. Sep 20, 2008 #2


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    You need 2 moles of water to 1 mole of CaH2. What ratio of reactants do you have? How does 1.29:0.80 compare with 2:1 ? Now, which is the limiting reactant? This is then what you use to determine the amount of hydrogen produced.
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