Question

Dihydrogen sulfide reacts with oxygen gas to form sulfur dioxide and water. How many moles of oxygen gas will react when 0.6469 moles of water are formed?

Answer 1

Answer: 0.9704 moles of $O_2$ will react when 0.6469 moles of water are formed.

Explanation:

The balanced chemical reaction is:

$2H_2S+3O_2(g)\rightarrow 2SO_2+2H_2O$  

According to stoichiometry :

2 moles of $H_2O$ are formed from = 3 moles of $O_2$

Thus 0.6469 moles of $H_2O$ are formed from =$\frac{3}{2}\times 0.6469=0.9704moles$  of $O_2$

Thus 0.9704 moles of $O_2$ will react when 0.6469 moles of water are formed.