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Lesson: Concentrations from Solubility Products

Worksheet • 17 Questions

Q1:

Clothing may be stained during washing if the water has a M n 2 + ion concentration 0.1 mg/L ( 1 . 8 Γ— 1 0 βˆ’ 6 M), but the amount of M n 2 + in the water can be reduced by adding a base. The base lowers the maximum value of [ M n ( ) 2 + a q ] by precipitating excess manganese ions as the hydroxide, M n ( O H ) 2 . The solubility product of M n ( O H ) 2 , 𝐾 s p , is 2 . 0 Γ— 1 0 βˆ’ 1 3 . Calculate to 1 decimal place the pH required to prevent [ M n 2 + ] from exceeding 1 . 8 Γ— 1 0 βˆ’ 6 M.

  • A10.5
  • B11.7
  • C7.0
  • D9.0
  • E8.2

Q2:

A solution contains 0.0010 mol of K I and 0.10 mol of K C l per liter. A g N O 3 is gradually added to this solution. Which forms first, solid A g I or solid A g C l ? 𝐾 s p is 1 . 6 Γ— 1 0 βˆ’ 1 0 for A g C l , and 1 . 5 Γ— 1 0 βˆ’ 1 6 for A g I .

  • ASolid A g I
  • BOnly solid A g N O 3 precipitates.
  • CSolid A g C l
  • DMore information is needed.
  • ESolid A g C l and solid A g I precipitate at the same value of [ A g ] . +

Q3:

A solution contains C l – and B r – ions at equal concentrations of 0.050 M. Silver(I) nitrate is added to the solution until precipitation takes place. The solubility product 𝐾 s p is 1 . 6 Γ— 1 0 βˆ’ 1 0 for A g C l , and 5 . 0 Γ— 1 0 βˆ’ 1 3 for A g B r .

At what value of [ A g + ] does precipitation begin?

  • A 1 . 0 Γ— 1 0 βˆ’ 1 1 M
  • B 6 . 2 Γ— 1 0 βˆ’ 1 2 M
  • C 5 . 0 Γ— 1 0 βˆ’ 1 0 M
  • D 9 . 9 Γ— 1 0 βˆ’ 1 1 M
  • E 3 . 3 Γ— 1 0 βˆ’ 1 2 M

To 3 significant figures, what molar percentage of the initial precipitate is A g C l ?

  • A0.00%
  • B99.7%
  • C100%
  • D0.313%
  • E50.0%

Q4:

Consider the equilibrium

A suspension contains solid M g ( O H ) 2 in equilibrium with a saturated solution of M g 2 + and O H – ions. The concentration of M g 2 + ions in the solution is 1 . 3 1 Γ— 1 0 βˆ’ 4 M. What is the solubility product of M g ( O H ) 2 ?

  • A 8 . 9 9 Γ— 1 0 βˆ’ 1 2
  • B 2 . 2 5 Γ— 1 0 βˆ’ 1 2
  • C 3 . 4 3 Γ— 1 0 βˆ’ 1 1
  • D 2 . 2 5 Γ— 1 0 βˆ’ 1 1
  • E 4 . 5 0 Γ— 1 0 βˆ’ 1 2

Q5:

Fluorite, C a F 2 , is a slightly soluble solid that dissolves according to the equation: The concentration of C a 2 + in a saturated solution of C a F 2 is 2 . 1 5 Γ— 1 0 βˆ’ 4 M. What is the solubility product of fluorite?

  • A 3 . 9 8 Γ— 1 0 βˆ’ 1 1
  • B 9 . 9 4 Γ— 1 0 βˆ’ 1 2
  • C 2 . 9 8 Γ— 1 0 βˆ’ 1 1
  • D 1 . 1 6 Γ— 1 0 βˆ’ 1 1
  • E 1 . 9 9 Γ— 1 0 βˆ’ 1 1

Q6:

Blood will not clot if calcium ions are removed from its plasma. Some blood collection tubes contain salts of the oxalate ion, C O 2 4 2 – , for this purpose. At sufficiently high concentrations, the calcium and oxalate ions form solid C a C O Β· H O 2 4 2 . The concentration of C a 2 + in a sample of blood serum is 2 . 2 Γ— 1 0 βˆ’ 3 M. What concentration of C O 2 4 2 – ions must be established before C a C O Β· H O 2 4 2 begins to precipitate? 𝐾 1 . 9 6 Γ— 1 0 s p 2 4 2 ( C a C O Β· H O ) = . βˆ’ 8

  • A 8 . 9 Γ— 1 0 βˆ’ 6 M
  • B 3 . 2 Γ— 1 0 βˆ’ 4 M
  • C 4 . 9 Γ— 1 0 βˆ’ 7 M
  • D 9 . 0 Γ— 1 0 βˆ’ 6 M
  • E 1 . 3 Γ— 1 0 βˆ’ 4 M

Q7:

The dissolution of silver(I) iodide is represented by the equation If this process changes [ A g ] + by an amount π‘₯ , what is the change in [ I ] – ?

  • A π‘₯
  • B 2 . 5 π‘₯
  • C 2 π‘₯
  • D 0 . 5 π‘₯
  • E 3 π‘₯

Q8:

The dissolution of magnesium phosphate is represented by the equation If this process changes [ M g ] 2 + by an amount π‘₯ , what is the change in [ P O ] 4 3 – ?

  • A 2 3 π‘₯
  • B 3 π‘₯
  • C π‘₯
  • D 2 π‘₯
  • E 3 2 π‘₯

Q9:

In an aqueous ammonia solution, N H 3 molecules react with A g + ions to form [ A g ( N H ) ] 3 2 + ions. The stability constant of [ A g ( N H ) ] 3 2 + is 1 . 7 Γ— 1 0 7 . If the concentration of [ A g ( N H ) ] 3 2 + ions in a solution is initially 0.10 M, what is the concentration of A g + ions at equilibrium?

  • A 1 . 1 Γ— 1 0 βˆ’ 3 M
  • B 1 . 8 Γ— 1 0 βˆ’ 3 M
  • C 7 . 7 Γ— 1 0 βˆ’ 4 M
  • D 3 . 1 Γ— 1 0 βˆ’ 4 M
  • E 7 . 2 Γ— 1 0 βˆ’ 3 M

Q10:

The iodate ion concentration of a saturated solution of L a ( I O ) 3 3 was found to be 3 . 1 Γ— 1 0 βˆ’ 3 mol/L. What is the 𝐾 s p of L a ( I O ) 3 3 ?

  • A 3 . 1 Γ— 1 0 βˆ’ 1 1
  • B 3 . 1 Γ— 1 0 βˆ’ 3
  • C 3 . 2 Γ— 1 0 βˆ’ 6
  • D 8 . 9 Γ— 1 0 βˆ’ 1 6
  • E 9 . 6 Γ— 1 0 βˆ’ 6

Q11:

The dissolution of calcium carbonate is represented by the equation If this process changes [ C O ] 3 2 – by an amount π‘₯ , what is the change in [ C a ] 2 + ?

  • A π‘₯
  • B 2 . 5 π‘₯
  • C 2 π‘₯
  • D 0 . 5 π‘₯
  • E 3 π‘₯

Q12:

The first step in the preparation of magnesium metal is the precipitation of M g ( O H ) 2 from sea water by the addition of C a ( O H ) 2 . The concentration of M g ( ) 2 + a q in sea water is 5 . 3 7 Γ— 1 0 βˆ’ 2 M and the solubility product of M g ( O H ) 2 is 8 . 9 Γ— 1 0 βˆ’ 1 2 . Calculate to 2 decimal places the pH at which the addition of C a ( O H ) 2 , causes [ M g 2 + ] to decrease to 1 . 0 Γ— 1 0 βˆ’ 5 M.

Q13:

The solubility product 𝐾 s p of A g C r O 2 4 at 2 5 ∘ C is 9 . 0 Γ— 1 0 βˆ’ 1 2 . If a solution contains 0.0020 mol of C r O 2 – 4 per liter, what concentration of A g + ion must be reached by adding solid A g N O 3 before A g C r O 2 4 begins to precipitate? Neglect any increase in volume upon adding the solid silver nitrate.

  • A 6 . 7 Γ— 1 0 βˆ’ 5 M
  • B 4 . 5 Γ— 1 0 βˆ’ 2 M
  • C 1 . 9 Γ— 1 0 βˆ’ 8 M
  • D 4 . 5 Γ— 1 0 βˆ’ 9 M
  • E 5 . 5 Γ— 1 0 βˆ’ 3 M

Q14:

The dissolution of magnesium hydroxide is represented by the equation If this process changes [ M g ] 2 + by an amount π‘₯ , what is the change in [ O H ] – ?

  • A 2 π‘₯
  • B 2 . 5 π‘₯
  • C π‘₯
  • D 0 . 5 π‘₯
  • E 3 π‘₯

Q15:

The dissolution of tribasic calcium phosphate is represented by the equation If this process changes [ C a ] 2 + by an amount π‘₯ , what is the change in [ P O ] 4 3 – ?

  • A 3 5 π‘₯
  • B π‘₯
  • C 5 3 π‘₯
  • D 3 π‘₯
  • E 5 π‘₯

Q16:

The 𝐾 s p of copper(II) iodate ( C u ( I O ) 3 2 ) is 7 . 4 Γ— 1 0 βˆ’ 8 . Calculate the concentration of iodate ions in a saturated solution of copper(II) iodate.

  • A 5 . 3 Γ— 1 0 βˆ’ 3 M
  • B 1 . 5 Γ— 1 0 βˆ’ 7 M
  • C 8 . 4 Γ— 1 0 βˆ’ 8 M
  • D 8 . 4 Γ— 1 0 βˆ’ 3 M
  • E 3 . 7 Γ— 1 0 βˆ’ 8 M

Q17:

A 1.00 L solution is prepared by dissolving 1.00 g of A g N O 3 and 10.0 g of K C N in water. A g + and C N – ions react to form [ A g ( C N ) ] 2 – ions, with a stability constant of 1 . 0 Γ— 1 0 2 1 . Calculate the concentration of A g + ions in the solution at equilibrium.

  • A 2 . 9 Γ— 1 0 βˆ’ 2 2 M
  • B 8 . 4 Γ— 1 0 βˆ’ 2 2 M
  • C 2 . 5 Γ— 1 0 βˆ’ 2 2 M
  • D 7 . 5 Γ— 1 0 βˆ’ 2 2 M
  • E 5 . 1 Γ— 1 0 βˆ’ 2 2 M
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