Question

2H2 + O2 → 2H2O

Answer 1

Answer : The number of moles of $O_2$ required are 0.835 moles.

Explanation : Given,

Moles of $H_2$ = 1.67 moles

The given balanced chemical reaction is,

$2H_2+O_2\rightarrow 2H_2O$

By the stoichiometry we can say that, 2 moles of hydrogen gas react with 1 mole of oxygen gas to give 2 moles of water as a product.

From the balanced reaction we conclude that,

As, 2 moles of $H_2$ react with 1 mole of $O_2$

So, 1.67 moles of $H_2$ react with $\frac{1.67}{2}=0.835$ mole of $O_2$

Therefore, the number of moles of $O_2$ required are 0.835 moles.

Answer 2

Mole ratio:

2 H2 + O2 =  2 H2O

2 mol H2 ---------- 1 mol O2
1.67 mol H2 ------ ??

1.67 x 1 / 2 => 0.835 moles of O2