Question

The reaction, N₂O₅ (g)$\rightleftarrows$2 NO₂ (g) +$\frac{1}{2}$ O₂ (g), is started with initial pressure of N₂O₅ (g) equal to 600 torr. What fraction of N₂O₅ (g) decomposed when total pressure of the system is 960 torr?

• A. 0.05
• B. 0.1
• C. 0.2
• D. 0.4

Answer 1

Answer: (D)

0.4

Answer 2

N₂O₅ (g) $\rightleftarrows$ 2 NO₂ (g) + $\frac{1}{2}$ O₂ (g)

Initially : 600 torr — —

At equilibrium: (600 – p) torr 2p torr $\frac{p}{2}$ torr

Total press is $\left( 600 + \frac{3p}{2} \right)$ torr

\ 600 + $\frac{3p}{2}$ = 960

or $\frac{3p}{2}$ = 360

or p = 240 torr

\fraction of N₂O₅ (g) decomposed = $\frac{240}{600}$= 0.4