Question

Find the number of moles of water that can be formed if you have 166 mol of hydrogen gas and 78 mol of oxygen gas. Express your answer with the appropriate units.

Answer 1

The balanced equation for the reaction is

2H2 (g) + O2(g) ----------------------> 2 H2O (l)

166 moles 78 moles - initial moles

To know the limiting regant , we calculate (given moles/ moles as per stichiometry) of each reactant.

The reactnat with less number ratio is limiting reagent.

166/2 =81 78/1 =78

Thus O2 with less ratio is limiting reagent and is consumed completely in the reaction to give product.

{alternativelyThe ratio of moles of H2 to O2 is 2;1 thus O2 is less than half the moles of H2.

Hence O2 is the limiting reagent.}

NOw the product is calculated from the moles of limiting reagent.

2H2 (g) + O2(g) ----------------------> 2 H2O (l)

166 moles 78 moles - initial moles

1 mole of O2 (g) gives 2 moles of H2O

78 mol of O2 can form = 78 mol of O2 x 2 mol of H2O / 1 mol of O2

= 156 mol of H2O