Question

Magnesium carbonate dissociates to magnesium oxide and carbon dioxide at elevated temperatures. MgCO3(s) MgO(s) + CO2(g) A reaction vessel contains these compounds in equilibrium at 300°C. What will happen if the volume of the container is reduced by 25% at 300°C? Multiple Choice The partial pressure of carbon dioxide present at equilibrium will increase. The partial pressure of carbon dioxide present at equilibrium will decrease. The partial pressure of carbon dioxide at equilibrium will be unchanged. The equilibrium constant will have to decrease to compensate for the decrease in volume. More information is needed in order to make a valid judgment.

Answer 1

When the volume of the container is reduced by 25% at 300°C, the partial pressure of carbon dioxide at equilibrium will increase.

Step-by-step explanation:

When the volume of the container is reduced by 25% at 300°C, the partial pressure of carbon dioxide at equilibrium will increase. This is because reducing the volume of the container increases the concentration of carbon dioxide, shifting the equilibrium towards the side with fewer moles of gas. In this case, the forward reaction produces one mole of CO₂ gas, while the reverse reaction produces one mole of solid MgCO₃ and one mole of solid MgO. As a result, increasing the concentration of CO₂ by reducing the volume of the container will push the equilibrium towards the product side, causing the partial pressure of CO₂ to increase.

Answer 2

The partial pressure of carbon dioxide present at equilibrium will decrease.

Step-by-step explanation:

Let's consider the following reaction.

MgCO₃(s) ⇄ MgO(s) + CO₂(g)

What will happen if the volume of the container is reduced by 25% at 300°C?

To answer this question we need to consider Le Chatelier's Principle: if a system at equilibrium suffers a perturbation, it will shift its equilibrium position to counteract such perturbation.

If the volume of the container is reduced, according to Boyle's Law, the pressure of the gases will increase. Thus, the system will try to decrease the pressure by favoring the reverse reaction because there are less gaseous moles in the reactants than in the products. As a consequence, the partial pressure of carbon dioxide present at equilibrium will decrease.