Question

At equilibrium, \([N_2] = 1.5 \times 10^{-3}M\), \([O_2] = 2 \times 10^{-3}M\) and \([NO] = 3 \times 10^{-3}M\) at 800 K in a closed vessel. The \(K_c\) for the equilibrium \(N_2(g) + O_2(g) \rightleftharpoons 2NO(g)\) at 800 K is}

• A. 1.0
• B. 0.3
• C. 2.0
• D. 4.0
• E. 3.0

Hint:

In equilibrium constant calculations, write the full expression first, then substitute carefully with brackets and powers.

Answer 1

Answer: (E)

For the reaction: \[ N_2 + O_2 \rightleftharpoons 2NO \] \[ K_c=\frac{[NO]^2}{[N_2][O_2]} \] Substitute the values: \[ K_c=\frac{(3\times10^{-3})^2}{(1.5\times10^{-3})(2\times10^{-3})} \] \[ =\frac{9\times10^{-6}}{3\times10^{-6}}=3 \]
Hence, the correct answer is: \[ \boxed{(E)\ 3.0} \]