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Solubility Concept Test

Problem 1

Consider a beaker containing 100ml of water, with solid AgCl on the bottom. If NaCl is added to the solution... (choose which two are true)

  1. The amount of AgCl solid at the bottom of the beaker increases.
  2. The amount of AgCl solid at the bottom of the beaker decreases.
  3. The concentration of [Ag+] in the solution stays the same
  4. The concentration of [Ag+] in the solution changes

Problem 2

The enamel covering of your teeth contains the mineral hydroxyapatite, Ca10(PO4)6(OH)2 which dissolves in water to give: Ca10(PO4)6(OH)2 (s) ⇌ 10 Ca+2 + 6PO4-3 + 2OH- Is hydroxyapatite more soluble in

  1. acidic solution
  2. neutral water
  3. basic solution

Problem 3

A buffer is prepared by adding 50.0ml of 0.15M HNO3 to 100ml of 0.12M NaHCOO (Sodium Formate). In this solution, will the ratio of [HCOO-]/ [HCOOH] be greater than, less than or equal to [F-]/[HF].

  1. [HCOO-]/ [HCOOH] > [F-]/[HF]
  2. [HCOO-]/ [HCOOH] = [F-]/[HF]
  3. [HCOO-]/ [HCOOH] < [F-]/[HF]
  4. We can't tell until we explicitly calculate the pH of the solution

Problem 4

Which of the following is correct?

  1. MgF2(s) <---> Mg2+(aq) + 2F-(aq)
  2. equil: excess x 2(1-0.7)x
  3. equil: excess x 2(1/0.7)x
  4. equil: excess x 2(0.7)x
  5. equil: excess x 2(1+0.7)x