Consider the reaction of hydrogen gas with chlorine gas: h2 + cl2 → 2hcl 4 molecules of hydrogen gas react with 6 molecules of chlorine gas. 4 molecules of hydrogen gas in this reaction will produce 8 molecules of hcl. 6 molecules of chlorine gas in this reaction will produce 12 molecules of hcl. which statement best describes the role of hydrogen in this chemical reaction? a) hydrogen is in excess. b) hydrogen serves as a catalyst. c) hydrogen is the limiting reactant. d) hydrogen inhibits the rate of reaction.

C. Hydrogen is the limiting reactant

Explanation:

Mole ratios are determined using the coefficients of the substances in the balanced chemical equation of reaction.

H2 + Cl2 > 2HCl

1mol:1mol 2mol

1mol of H2 reacts with 1 mole Cl2 to produce 2 moles of HCl.

From the above question, the amount of moles for H2 and for Cl2 are given as well as the amount of HCl each will produce.

We know the following now:

•1 mole of H2 gives 2 moles of HCl. •Thus, 4 molecules of H2 will produce 8 molecules of HCl.

•4 molecules of Cl2 will also produce 8 molecules of HCl.

•Likewise, 6 molecules of Cl2 will produce 12 molecules of HCl

•6 molecules of H2 will also produce 12 molecules of HCl BUT we do not have 6 molecules of H2 (From the question) .

This makes us short of H2 molecules. That is, the amount of H2 is in limited supply, which makes H2 the limiting reactant while Cl2 is in excess.

Therefore, we can only make 8 moles of HCl instead of 12 moles.

The best statement which describes the role of hydrogen in this chemical reaction is that hydrogen is the limiting reactant.