Ammonia and oxygen react to form nitrogen monoxide and water, like this:

4NH3(g) + 5O2(g) → 4NO(g) + 6H2O(g)

Also, a chemist finds that at a certain temperature the equilibrium mixture of ammonia, oxygen, nitrogen monoxide, and water has the following composition:

Compound Pressure at equilibrium
NH3 36.2atm
O2 77.6atm
NO 87.8atm
H2O 9.77atm

Calculate the value of the equilibrium constant Kp for this reaction.

Kp = 0.0107

Explanation:

The reaction:

4 NH₃ (g) + 5O₂ (g)  →  4NO (g)  + 6H₂O(g)

Let's make the expression for Kp, similar to Kc but, we use the partial pressures:

Kp = (Partial Pressure NO)⁴ . (Partial Pressure H₂O)⁶ / (Partial pressure O₂)⁵ . (Partial Pressure NH₃)⁴

Kp = 87.8⁴ . 9.77⁶  / 77.6⁵ . 36.2⁴

Kp = 5.17×10¹³ / 4.83×10¹⁵ → 0.0107

a chemical reaction

explanation:

c is the answer because when something is left after something evaporates that shows the chemical change.