Question

For the equilibrium at ${27}^{o}C.$
$LiCl.3N{H}_3\left(s\right)\rightleftharpoons LiCl.N{H}_3\left(s\right)+2N{H}_3\left(g\right);K_P=9at{m}^2$
A 24.63 litre flask contain 1 mol $LiCl.N{H}_3.$ How many moles of $N{H}_3$ should be added to flask at this temperature to drive the backward reaction for completion.

• A. 5 moles
• B. 8 moles
• C. 3 moles
• D. 2 moles

Answer 1

The correct option is A 5 moles

Given: $K_P=9at{m}^2$ = $P_{N{H}_3}^2$
$P_{N{H}_3}=9at{m}^2$
$P_{N{H}_3}=3atm$
Using, PV = nRT
$3\times 24.63=n_{N{H}_3}\times R\times 300$
$n_{N{H}_3}=3$ (at equilibrium)
$LiCl.3N{H}_3\left(s\right)\rightleftharpoons LiCl.N{H}_3\left(s\right)+2N{H}_3\left(g\right)$
1 n
0 n - 2
Now, we know, $n-2=3$
n = 5 moles