Question

Match the effects on the concentration of SO2 gas when the following changes occur after initial equilibrium has been established in this system:

2SO2(g) + O2(g) 2SO3(g) + 46.8 kcal

pressure increases

increase [O2]

increase volume of chamber

adding a catalyst

raising the temperature

Answer 1

Did you have ideas on what each one might be, using Le Chatelier's Principle?

Answer 2

For pressure changes, increasing the pressure forces equilibrium towards the side with the least amount of moles of gas. This is because they are limited in space so they want to minimize the amount of particles. So you can count the coefficients on each side to determine which has more or less moles. The side with less is where equilibrium shifts. The opposite happens when pressure decreases, or volume increases.

Increasing the concentration of one material on one side favors the opposite side.

Catalysts have NO effect on equilibrium. They do not interact with the material, they only facilitate the reaction itself to increase its speed. But it favors both sides equally.

Lastly, temperature changes want to minimize the stress of heat by consuming additional energy. So higher temperatures will shift equilibrium in the direction of an endothermic reaction (the one that absorbs heat). In this case, as temperature increases equilibrium shifts towards the left-hand side because from right to left is the endothermic reaction.