The Effect of Pressure Changes on Equilibrium Flashcards

All 5 cards in this deck

What effect does an increase in pressure have on the position of equilibrium?

It shifts towards the side with the smaller number of gas molecules shown in the symbol equation.

What effect does a decrease in pressure have on the position of equilibrium?

It shifts towards the side with the larger number of gas molecules shown in the symbol equation.

When does changing the pressure have no effect on the position of equilibrium?

When there are equal numbers of gas molecules on each side of the equation.

e.g. $2\mathrm{HI(g)} \rightleftharpoons \mathrm{H_2(g)} + \mathrm{I_2(g)}$

True or false? Changing the pressure shifts the equilibrium position of a reaction between aqueous solutions.

False. There is no change in equilibrium position because no gases are present.

What are the steps to predict the effect of increasing the pressure on a gaseous equilibrium?

e.g. $2\mathrm{NO_2(g)}$ (brown) $\rightleftharpoons \mathrm{N_2O_4(g)}$ (colourless)

1. Count the gas molecules on each side: 2 on the left, 1 on the right.
2. Increased pressure shifts equilibrium to the side with fewer molecules: the right.
3. More $\mathrm{N_2O_4}$ forms, so the mixture becomes a lighter shade of brown.