Question

A sample of carbon is placed in a rigid 1.50 L flask. Dinitrogen monoxide is added and the flask heated to 800C. When the system reached equilibrium the partial pressure of the carbon dioxide is found to be 0.030 atm and the partial pressure of the dinitrogen monoxide to be 1.48 atm. What will be the sign of the change in entropy, delta S, for the reaction?

Answer 1

The sign of `ΔS` for the forward reaction is positive.

The balanced equation is

C(s) + 2N₂O(g) ⇌ CO₂(g) + 2N₂(g)

You started with only carbon and dinitrogen monoxide. So the reaction is proceeding to the right to reach equilibrium.

There are 3 mol of gas on the right and only 2 mol of gas on the left.

So entropy is increasing, and `ΔS` > 0.