Question

For the reaction, $N_2{O}_5\left(g\right)\rightleftharpoons 2N{O}_2\left(g\right)+1/2O_2\left(g\right)$, calculate the mole fraction of $N_2{O}_5\left(g\right)$ decomposed at a constant volume and temperature, if the initial pressure is $600mmHg$ and the pressure at any time is $960mmHg$. Assume ideal gas behaviour. If answer is $x$ then report $10x$.

Answer 1

For the reaction

$N_2{O}_5\left(g\right)\rightleftharpoons 2N{O}_2\left(g\right)+1/2O_2\left(g\right)$

Initial partial pressure:

$600mmHg00$

At time $t$

$600-x2x0.5x$

Pressure=$960mmHg$

$\therefore 960=600-x+2x+0.5x$

$1.5x=360$

$x=240mmHg$

partial pressure of $N_2{O}_5=p_{N_2{O}_5}=600-240=360mmHg$

Since ${\chi }_A\times P=p_A$

$\therefore {\chi }_{N_2{O}_5}\times 960=360$

$\therefore {\chi }_{N_2{O}_5}=0.375$

and $10x=3.75$ is the answer.