Question

An amount of solid $N{H}_{4}HS$ is placed in a flask already containing ammonia gas at a certain temperature and $0.50$ atm pressure Ammonium hydrogen sulphide decomposes to yield $N{H}_3$ and $H_{2}S$ gases in the flask. When the decomposition reaction reaches equilibrium, the total pressure in the flask rises to $0.84$ atm. The equilibrium constant for $N{H}_{4}HS$ decomposition at this temperature is:

• A. $0.11$
• B. $0.17$
• C. $0.18$
• D. $0.30$

Answer 1

The correct option is A $0.11$

${NH}_{4}H{S}_{\left(S\right)}⟶{NH}_3\left(g\right)+H_2{S}_{\left(S\right)}$

start $0.5$atm $0$atm

at equilibrium $0.5$atm+$x$ $x$atm

$0.5+x+x=2x+0.5=0.84$

$x=0.17$atm

${PNH}_3=0.5+0.17=0.67$atm

${PH}_{2}S=0.17$atm

$K={PNH}_3\times {PH}_{2}S=0.67\times 0.17=0.11{atm}^2$