Question

For the reaction$4N{H}_3\left(g\right)+5O_2\left(g\right)\rightleftharpoons 4NO\left(g\right)+6H_{2}O\left(g\right),$, the expression of $K_c$ will be:

• A. $K_c=\frac{\left[NO{]}^4\right[H_{2}O{]}^6}{\left[N{H}_3{]}^4\right[O_2{]}^5}$
• B. $K_c=\frac{\left[N{H}_3{]}^4\right[O_2{]}^5}{\left[NO{]}^4\right[H_{2}O{]}^6}$
• C. $K_c=\frac{\left[N{H}_3\right]\left[O_2\right]}{\left[NO\right]\left[H_{2}O\right]}$
• D. $K_c=\frac{\left[NO\right]\left[H_{2}O\right]}{\left[N{H}_3\right]\left[O_2\right]}$

Answer 1

The correct option is A $K_c=\frac{\left[NO{]}^4\right[H_{2}O{]}^6}{\left[N{H}_3{]}^4\right[O_2{]}^5}$

$4N{H}_3\left(g\right)+5O_2\left(g\right)\rightleftharpoons 4NO\left(g\right)+6H_{2}O\left(g\right),$
The reaction is an example of homogenous reaction
As per the law of mass action, rate of a reaction is proportional to the product of active masses of reactants and products raised to the powers of their stoichiometric coefficients.
So, $K_c=\frac{\left[NO{]}^4\right[H_{2}O{]}^6}{\left[N{H}_3{]}^4\right[O_2{]}^5}$