Question

Consider the following gas phase reaction:

2NO(g) + O2(g) --> 2NO2(g)

400. mL of NO at STP is reacted with 500. mL of O2 at STP. Calculate the volume of the reaction mixture at STP after the reaction goes to completion.

A.700 mL
B.800 mL
C.900 mL
D.1300 mL
E.100 mL

The answer is A. 700 mL, can someone please explain how they arrived at that answer.

Answer 1

Answer

2NO(g) + O2(g) --> 2NO2(g)

now 400 ml of NO × 2 mol of NO2/2 mol of NO

= 400 ml of NO2

now 500 ml of O2 × 2 mol of NO2/1 mol of O2

= 1000 ml of NO2

now 400 ml of NO2 × 1 mol of O2/2 mol of NO

= 200 ml

subtract that from 500 ml of total i.e. 500-200 =300 ml

The total volume of the reaction mixture is 1000 ml -300ml = 700 ml