Question

An initial mixture of nitrogen gas and hydrogen gas is reacted in a rigid container at a certain temperature as follows: 3H2(g) 1 N2(g) 34 2NH3(g) At equilibrium, the concentrations are [H2] 5 5.0 M, [N2] 5 8.0 M, and [NH3] 5 4.0 M. What were the con- centrations of nitrogen gas and hydrogen gas that were reacted initially?

Answer 1

Answer : The concentration of nitrogen gas and hydrogen gas that reacted initially are 10.0 M and 11.0 M respectively.

Solution : Given,

Concentration of
`H_2` at equilibrium = 5.0 M

Concentration of
`N_2` at equilibrium = 8.0 M

Concentration of
`NH_3` at equilibrium = 4.0 M

The given equilibrium reaction is,

`3H_2(g)+N_2(g)\rightleftharpoons 2NH_3(g)`

Initially a b 0

Change -3x -x +2x

At equilibrium (a-3x) (b-x) +2x

As we are given that,

Concentration of
`NH_3` at equilibrium = 4.0 M = 2x

That means,

2x = 4.0

x = 2.0

Now we have to calculate the concentration of nitrogen gas and hydrogen gas that were reacted initially.

Concentration of
`H_2` :

`a-3x=5.0\\\\a-3* 2.0=5.0\\\\a=11.0M`

Concentration of
`N_2` :

`b-x=8.0\\\\b-2.0=8.0\\\\b=10.0M`

Therefore, the concentration of nitrogen gas and hydrogen gas that reacted initially are 10.0 M and 11.0 M respectively.