Question

Hydrogen iodide can decompose into hydrogen and iodine gases. 2HI(g) H2(g) I2(g) K for the reaction is 0.016. Of 0.148 atm of HI(g) is sealed in a flask, what is the pressure of each gas when equilibrium is established

Answer 1

Given :

Hydrogen iodide decomposes to hydrogen and iodine gas

`$2 HI \ \ \ \Leftrightarrow \ \ \ \ H_2 \ \ \\ + \ \ I_2 $`

I 0.148 0 0

C -2a +a +a

E 0.148-2a a a

We know

`$k_p=(P(H_2)P(I_2))/(P(HI)^2)$`

`$0.016=(a^2)/((0.148-2a)^2)$`

`$0.016^(1/2)=(a)/(0.148-2a)$`

`$0.12649=(a)/(0.148-2a)$`

0.0187 = 1.2529 a

a = 0.0149

Therefore

P(HI) = 0.148 - 2a

= 0.148 - 2(0.0149)

= 0.1182 atm

P(
`$H_2$`) = a

= 0.0149 atm

P(
`$I_2$`) = a

= 0.0149 atm