Question

A sample of pure NO2 gas heated to 1000 K decomposes : 2NO2(g) 2NO(g) + O2(g). The equilibrium constant KP is 100 atm. Analysis shows that the partial pressure of O2 is 0.25 atm. at equilibrium. The partial pressure of NO2 at equilibrium is:

• A. 0.03
• B. 0.25
• C. 0.025
• D. 0.04b

Answer 1

Answer: (C)

0.025

Answer 2

2NO2 $\rightleftharpoons$ 2NO(g) + O2(g)

$\mathrm { K } _ { \mathrm { p } } = \frac { \left( \mathrm { p } _ { \mathrm { NO } } \right) ^ { 2 } \left( \mathrm { P } _ { \mathrm { O } _ { 2 } } \right) } { \left( \mathrm { P } _ { \mathrm { NO } _ { 2 } } \right) ^ { 2 } }$

given

PO2 = 0.25 ; PNO = 0.5

$\left( \mathrm { P } _ { \mathrm { NO } 2 } \right) ^ { 2 } = \frac { ( 0.5 ) ^ { 2 } ( 0.25 ) } { 100 }$

PNO2 = 0.025