Explanation:

In this reaction, N2 and H2 react to form NH3 according to the following balanced equation:

N2 + 3H2 → 2NH3

The molar ratio between N2 and H2 is 1:3, which means that for every 1 mole of N2, 3 moles of H2 are required.

Step 1: Determine the moles of N2 and H2:

Let's assume that we have x moles of N2. Since the molar ratio between N2 and H2 is 1:3, we will have 3x moles of H2.

Step 2: Calculate the moles of NH3 produced:

According to the balanced equation, 1 mole of N2 reacts with 3 moles of H2 to produce 2 moles of NH3. Therefore, the moles of NH3 produced will be 2x.

Step 3: Calculate the moles of N2, H2, and NH3 remaining:

Since only 50% of the reaction has taken place, the moles of N2, H2, and NH3 remaining will be half of the initial moles. Therefore, the moles of N2 remaining will be 0.5x, the moles of H2 remaining will be 1.5x, and the moles of NH3 remaining will be x.

Step 4: Calculate the total pressure at equilibrium:

The total pressure at equilibrium is the sum of the partial pressures of each component. Since the volume and temperature are constant, the partial pressure of each component is directly proportional to its moles.

The partial pressure of N2 at equilibrium is 0.5x times the total pressure P.
The partial pressure of H2 at equilibrium is 1.5x times the total pressure P.
The partial pressure of NH3 at equilibrium is x times the total pressure P.

Step 5: Calculate the pressure of NH3 at equilibrium:

Since the total pressure at equilibrium is P, and the partial pressure of NH3 is xP, the pressure of NH3 at equilibrium is xP.

Therefore, the pressure of NH3 at equilibrium in terms of P is xP.

Summary:

- The molar ratio between N2 and H2 is 1:3.
- At equilibrium, 50% of the reaction has taken place.
- The moles of N2 remaining are 0.5x, the moles of H2 remaining are 1.5x, and the moles of NH3 remaining are x.
- The total pressure at equilibrium is the sum of the partial pressures of each component.
- The pressure of NH3 at equilibrium in terms of P is xP.