Chapter 15 - Equilibrium

Question 1

When can you cancel out the x? (Hint: rule of 100)

Answer 1

You can cancel it out when the change in concentration or pressure is significantly smaller than the initial concentration so x essentially equals the initial concentration.

You do this by

x/initial > 100
If greater than 100, than insignificant enough you justified assumption to exclude it

Question 2

Two different salts, 𝐴2𝑋 and 𝐵𝑌3 have identical values of 𝐾𝑠𝑝, but have different
molar solubilities. Briefly explain how that can be true

Answer 2

They have different dissolution stoichiometries. Ksp is the product of concentrations at equilibrium. If a salt dissociates into more ions, concentration of these ions will be higher, so molar solubility must be smaller to keep Ksp constant. Salt must dissolve less to avoid making product of ion concentrations too large.

So when A2X dissociates it produces three ions and when BY3 dissociates it produces 4 ions.

Question 3

Define activity

Answer 3

Effective concentrations or pressures for real gases factoring in particle interactions