Question

When solid NH4HS is placed in a closed flask at 28oC, the solid dissociates according to the equation below. NH4HS(s) ⇄ NH3(g) + H2S(g). The total pressure of the equilibrium mixture is 0.766 atm. Determine Keq at this temperature.

Answer 1

Answer: 0.147

Explanation:

$K_p$ is the constant of a certain reaction at equilibrium.

For the given chemical reaction:

     $NH_4HS(s)\rightleftharpoons NH_3(g)+H_2S(g)$

at t= 0       0                                           0               0

at eqm                                                   p                p

Total pressure = p+p = 0.766 atm

2p= 0.766 atm

p= 0.383 atm

The expression of $K_p$ for above equation follows:

$K_p={p_{NH_3}\times p_{H_2S}}$

We are given:

$K_p={0.383\times 0.383$

$K_p=0.147$

Thus $K_{eq}$ at this temperature is 0.147