ANSWER
Keq is 3798.42 or 3.798 x 10^3
EXPLANATION
Given that;
The concentration of NH3 is 0.31M
The concentration of N2 is 0.85M
The concentration of H2 is 0.031M
Follow the steps below to find the chemical equilibrium constant of the reaction
Step 1; Write the balanced equation of the reaction
[tex]\text{ N}_{2(g)}\text{ + 3H}_{2(g)}\text{ }\rightleftarrows\text{ 2NH}_{3(g)}[/tex]Step 2; Write the chemical equilibrium constant for the reaction
[tex]\begin{gathered} \text{ K}_{eq}\text{ = }\frac{K_f}{\text{ K}_b} \\ \text{ Where} \\ \text{ K}_f\text{ = }\lbrack NH_3\rbrack^2 \\ \text{ K}_b\text{ = }\lbrack N_2\rbrack\text{ }\lbrack H_2\rbrack^3 \end{gathered}[/tex]Step 3; Substitute the kf and kb into the formula above
[tex]\text{ K}_{eq}\text{ = }\frac{\lbrack NH_3\rbrack^2}{\lbrack H_2\rbrack^3\times\lbrack N_2\rbrack}[/tex]Recall, that
[NH3] = 0.31M
[H2] = 0.031M
[N2] = 0.85M
[tex]\begin{gathered} \text{ K}_{eq}\text{ = }\frac{(0.31)^2}{(0.85)\times\text{ \lparen0.031\rparen}^3} \\ \\ \text{ K}_{eq}\text{ = }\frac{\text{ 0.0961}}{0.85\text{ }\times\text{ 0.0000298}} \\ \\ \text{ K}_{eq}\text{ = }\frac{\text{ 0.0961}}{0.0000253} \\ \\ \text{ K}_{eq}\text{ = 3798.42 or 3.798 }\times\text{ 10}^3 \end{gathered}[/tex]Therefore, Keq is 3798.42 or 3.798 x 10^3