Equilibrium Question 626
Question: An amount of solid $ NH_4HS $ is placed in a flask already containing ammonia gas at a certain temperature and 0.50 atm. pressure. Ammonium hydrogen sulphide decomposes to yield $ NH_3 $ and $ H_2S $ 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 $ NH_4HS $ decomposition at this temperature is [AIEEE 2005]
Options:
A) 0.30
B) 0.18
C) 0.17
D) 0.11
Show Answer
Answer:
Correct Answer: D
Solution:
$ \underset{a-x}{\mathop{\underset{a}{\mathop{NH_4HS}},}}, $ ⇌ $ \underset{0.5+x,x}{\mathop{\underset{0.5atm,}{\mathop{N{H_{3,(g)}}+H_2{S_{(g)}}}},}}, $ Total pressure $ =0.5+2x=0.84 $ i.e., $ x=0.17 $
$ K_{p}={P_{NH_3}}.{P_{H_2S}} $
$ =(0.67).,(0.17) $ =0.1139
