Hydrogen iodide, HI, is formed in an equilibrium reaction when gaseous hydrogen and iodine gas are heated together. If 20.0 g of hydrogen and 20.0 g of iodine are heated, forming 10.0 g of hydrogen iodide, what mass of hydrogen remains unreacted?

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19.9 g hydrogen remains unreacted.The balanced chemical equation is:H2 + I2 <=> 2HIThe molar mass of hydrogen is 2.02 g/mol, and the molar mass of iodine is 253.8 g/mol. Therefore, 20.0 g of hydrogen is equal to 9.90 mol of hydrogen, and 20.0 g of iodine is equal to 0.079 mol of iodine.The mole ratio of hydrogen to iodine in the balanced chemical equation is 1:1. Therefore, the limiting reactant is iodine.The theoretical yield of hydrogen iodide is:0.079 mol I2 * (2 mol HI / 1 mol I2) * (127.9 g HI / 1 mol HI) = 20.0 g HISince only 10.0 g of hydrogen iodide is formed, the percent yield is:(10.0 g HI / 20.0 g HI) * 100% = 50.0%Therefore, 19.9 g of hydrogen remains unreacted.

Hydrogen Iodide, HI, Is Formed in an Equilibrium Reaction When