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 [tex]H_2[/tex] at equilibrium = 5.0 M
Concentration of [tex]N_2[/tex] at equilibrium = 8.0 M
Concentration of [tex]NH_3[/tex] at equilibrium = 4.0 M
The given equilibrium reaction is,
[tex]3H_2(g)+N_2(g)\rightleftharpoons 2NH_3(g)[/tex]
Initially a b 0
Change -3x -x +2x
At equilibrium (a-3x) (b-x) +2x
As we are given that,
Concentration of [tex]NH_3[/tex] 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 [tex]H_2[/tex] :
[tex]a-3x=5.0\\\\a-3\times 2.0=5.0\\\\a=11.0M[/tex]
Concentration of [tex]N_2[/tex] :
[tex]b-x=8.0\\\\b-2.0=8.0\\\\b=10.0M[/tex]
Therefore, the concentration of nitrogen gas and hydrogen gas that reacted initially are 10.0 M and 11.0 M respectively.