Starting with 9.3 moles of O2, how many moles of H2S will be needed and how many moles of SO2 will be produced in the following reaction? 2 H2S + 3 O2  2 SO2 + 2 H2O

Question

Can you please explain how you got the answer. thank you

Answer 1

Chemical reactions occur in stoichiometric ratios, meaning that for a certain amount of reactant consumed a certain amount of product will be created. In this case, our ratio is that for ever 3 moles of oxygen consumed, we also consume 2 moles of dihydrogen sulfide and produce two moles of sulfur dioxide. We need to set up a proportion to determine how many moles of H2S we will consume if we consume 9.3 moles of oxygen, and a second proportion to determine how many moles of SO2 will be created.

Proportion 1:

9.3/3=x/2, where 9.3 is the new number of moles of O2, and 3 and 2 are the stoichiometric coefficients of O2 and H2S in the reaction.

Solving for x yields that we need 6.2 moles of H2S to use all of the O2.

Proportion 2:

This is actually the exact same math as Proportion 1 since H2S and SO2 have the same stoichiometric coefficients, which means that we will produce 6.2 moles of SO2.