Question

Suppose that 4.2 mol NO2 and 0.20 mol H2O combine and react completely. Which reactant is in excess?

Answer 1

Answer 2

ANSWER :

Reaction of NO2 and H2O is as under :

3NO2 + H2O = 2HNO3 + NO 

=> 3 moles of NO2 reacts with 1 mole of H2O to produce 2 moles of nitric acid and 1 mole of NO.

There are 4.2 moles of NO2 and 0.20 moles of H2O.

So, 0.20 moles of  water will react with 3*0.20 = 0.060 moles of NO2 only,

and 4.2 - 0.6 = 3.6 moles of NO2 are unreacted or are in excess.

Hence, NO2 is in excess. (ANSWER).