Équilibres de solubilité

Question 1

Define solubility of a sparingly soluble salt

Answer 1

conc referring to max amt of solute (in g or mol) that can b dissolved in 1dm³ of solvent to make saturated sol n at given temp

Question 2

Define solubility product (Ksp) of a sparingly soluble salt

Answer 2

eqm const which is pdt of molar conc of dissolved associated ions (each raised to appropriate pwr) in saturated sol n of salt at given temp

Question 3

Define common ion effect

Answer 3

solubility of a sparingly soluble salt is decreased in presence of common ion fr external source

Question 4

What is the relationship between ionic product and Ksp? (HINT: what occurs?)

Answer 4

When:
-ionic pdt > Ksp (beyond saturation pt), precipitation occurs
-ionic pdt = Ksp (Saturation pt) OR ionic pdt < Ksp (lower than saturation pt), no precipitation occurs

Question 5

What to take note of when two solutions are mixed?

Answer 5

NEW total volume must be calculated to obtain NEW conc.

Question 6

Define ionic product

Answer 6

pdt of molar conc of dissolved dissociated ions (each raised to appropriate pwr) in sol n at given temp (at any pt in time)

Question 7

What is the difference between Ksp and Ionic Product?

Answer 7

Ksp is const at const temp. Ionic pdt not const; depends on conc of rxt or situation

eg
MX(s) ⇌ M+(aq) + X-(aq)

Ksp = [M+]eqm[X-]eqm (eqm conc.)
vs
Ionic product = [M+][X-] (to be calculated based on given info)

Question 8

What is the general effect of complex ion form n on salt solubility?

Answer 8

• solubility of sparingly soluble salt increases w add n of reagent that reacts w cation (or anion) to form complex ions
• add n of complexing reagent decreases conc of cation (or anion)
• By LCP, eqm pos n of (1) shift right to increase conc of cation (or anion), so more of sparingly soluble salt dissolves