Worksheet: Concentrations from Solubility Products

In this worksheet, we will practice using the solubility product of an ionic material to find the concentrations of dissolved ions.


The dissolution of tribasic calcium phosphate is represented by the following equation. Ca(PO)OH()5Ca()+3PO()+OH()5432+43saqaqaq If this process changes [Ca]2+ by an amount 𝑥, what is the change in [PO]43?

  • A𝑥
  • B5𝑥
  • C53𝑥
  • D35𝑥
  • E3𝑥


The dissolution of magnesium phosphate is represented by the following equation. Mg(PO)()3Mg()+2PO()3422+43saqaq If this process changes [Mg]2+ by an amount 𝑥, what is the change in [PO]43?

  • A32𝑥
  • B3𝑥
  • C23𝑥
  • D𝑥
  • E2𝑥


The dissolution of magnesium hydroxide is represented by the following equation. Mg(OH)()Mg()+2OH()22+saqaq If this process changes [Mg]2+ by an amount 𝑥, what is the change in [OH]?

  • A3𝑥
  • B2𝑥
  • C0.5𝑥
  • D𝑥
  • E2.5𝑥


The dissolution of calcium carbonate is represented by the following equation. CaCO()Ca()+CO()32+32saqaq If this process changes [CO]32 by an amount 𝑥, what is the change in [Ca]2+?

  • A0.5𝑥
  • B2𝑥
  • C3𝑥
  • D2.5𝑥
  • E𝑥


The dissolution of silver(I) iodide is represented by the following equation. AgI()Ag()+I()saqaq+ If this process changes [Ag]+ by an amount 𝑥, what is the change in [I]?

  • A2.5𝑥
  • B2𝑥
  • C3𝑥
  • D0.5𝑥
  • E𝑥


A 1.00 L solution is prepared by dissolving 1.00 g of AgNO3 and 10.0 g of KCN in water. Ag+ and CN ions react to form [Ag(CN)]2 ions, with a stability constant of 1.0×10. Calculate the concentration of Ag+ ions in the solution at equilibrium.

  • A2.5×10 M
  • B7.5×10 M
  • C5.1×10 M
  • D2.9×10 M
  • E8.4×10 M


In an aqueous ammonia solution, NH3 molecules react with Ag+ ions to form [Ag(NH)]32+ ions. The stability constant of [Ag(NH)]32+ is 1.7×10. If the concentration of [Ag(NH)]32+ ions in a solution is initially 0.10 M, what is the concentration of Ag+ ions at equilibrium?

  • A1.1×10 M
  • B3.1×10 M
  • C7.7×10 M
  • D7.2×10 M
  • E1.8×10 M


The first step in the preparation of magnesium metal is the precipitation of Mg(OH)2 from sea water by the addition of Ca(OH)2. The concentration of Mg()2+aq in sea water is 5.37×10 M and the solubility product of Mg(OH)2 is 8.9×10. Calculate to 2 decimal places the pH at which the addition of Ca(OH)2 causes [Mg]2+ to decrease to 1.0×10 M.


Clothing may be stained during washing if the water has a Mn2+ ion concentration of 0.1 mg/L (1.8×10 M), but the amount of Mn2+ in the water can be reduced by adding a base. The base lowers the maximum value of [Mn()2+aq] by precipitating excess manganese ions as the hydroxide, Mn(OH)2. The solubility product of Mn(OH)2, 𝐾sp, is 2.0×10. Calculate to 1 decimal place the pH required to prevent [Mn2+] from exceeding 1.8×10 M.


The solubility product 𝐾sp of AgCrO24 at 25C is 9.0×10. If a solution contains 0.0020 mol of CrO24 per liter, what concentration of Ag+ ion must be reached by adding solid AgNO3 before AgCrO24 begins to precipitate? Neglect any increase in volume upon adding the solid silver nitrate.

  • A4.5×10 M
  • B4.5×10 M
  • C1.9×10 M
  • D5.5×10 M
  • E6.7×10 M


A solution contains Cl and Br ions at equal concentrations of 0.050 M. Silver(I) nitrate is added to the solution until precipitation takes place. The solubility product 𝐾sp is 1.6×10 for AgCl and 5.0×10 for AgBr.

At what value of [Ag]+ does precipitation begin?

  • A6.2×10 M
  • B3.3×10 M
  • C9.9×10 M
  • D5.0×10 M
  • E1.0×10 M

To 3 significant figures, what molar percentage of the initial precipitate is AgCl?

  • A0.313%
  • B50.0%
  • C100%
  • D99.7%
  • E0.00%


A solution contains 0.0010 mol is KI and 0.10 mol for KCl. AgNO3 is gradually added to this solution. Which forms first, solid AgI or solid AgCl? 𝐾sp is 1.6×10 for AgCl, and 1.5×10 for AgI.

  • AOnly solid AgNO3 precipitates.
  • BSolid AgCl
  • CMore information is needed.
  • DSolid AgCl and solid AgI precipitate at the same value of [Ag].+
  • ESolid AgI


Blood will not clot if calcium ions are removed from its plasma. Some blood collection tubes contain salts of the oxalate ion, CO242, for this purpose. At sufficiently high concentrations, the calcium and oxalate ions form solid CaCO·HO242. The concentration of Ca2+ in a sample of blood serum is 2.2×10 M. What concentration of CO242 ions must be established before CaCO·HO242 begins to precipitate? Consider 𝐾1.96×10sp242(CaCO·HO)=.

  • A1.3×10 M
  • B9.0×10 M
  • C3.2×10 M
  • D8.9×10 M
  • E4.9×10 M


Consider the following equilibrium. Mg(OH)()Mg()+2OH()22+saqaq

A suspension contains solid Mg(OH)2 in equilibrium with a saturated solution of Mg2+ and OH ions. The concentration of Mg2+ ions in the solution is 1.31×10 M. What is the solubility product of Mg(OH)2?

  • A4.50×10
  • B3.43×10
  • C2.25×10
  • D2.25×10
  • E8.99×10


Fluorite, CaF2, is a slightly soluble solid that dissolves according to the following equation. CaF()Ca()+2F()22+saqaq The concentration of Ca2+ in a saturated solution of CaF2 is 2.15×10 M. What is the solubility product of fluorite?

  • A3.98×10
  • B2.98×10
  • C1.16×10
  • D1.99×10
  • E9.94×10


The iodate ion concentration of a saturated solution of La(IO)33 was found to be 3.1×10 mol/L. What is the 𝐾sp of La(IO)33?

  • A3.1×10
  • B8.9×10
  • C3.2×10
  • D9.6×10
  • E3.1×10


The 𝐾sp of copper(II) iodate (Cu(IO)32) is 7.4×10. Calculate the concentration of iodate ions in a saturated solution of copper(II) iodate.

  • A1.5×10 M
  • B3.7×10 M
  • C8.4×10 M
  • D5.3×10 M
  • E8.4×10 M


The acid dissociation constant, 𝐾a, of HCN is 4.9×10 and the solubility product, 𝐾sp, of Mg(OH)2 is 8.9×10. To 2 significant figures, what mass of NaCN must be added to 1.00 L of 0.010 MMg(NO)32 to initiate the precipitation of Mg(OH)2?

  • A6.6×10 g
  • B1.2×10 g
  • C3.3×10 g
  • D4.9×10 g
  • E7.7×10 g


Which of the following compounds, when dissolved in a 0.01 M solution of HClO4, has a solubility greater than in pure water?

  • ABaF2
  • BTl(NO)32
  • CPbI2
  • DNaCl
  • EAgBr


If solid Mg(OH)2 was added to 0.01 M aqueous solutions of the following compounds, which of them will decrease the solubility of Mg2+ ions?

  • AMg(OH)2
  • BNaNO3
  • CMgCl2
  • DHClO4
  • ENaCl


In a solution buffered at a pH of 11.45 in contact with solid Zn(OH)2, what is [Zn]2+ at equilibrium? The 𝐾sp of Zn(OH)2 is 3.0×10 and the self-ionization constant of water, 𝐾w, is 1.0×10.

  • A4.2×10 M
  • B3.8×10 M
  • C5.7×10 M
  • D3.3×10 M
  • E9.1×10 M


An unbuffered solution initially at a pH of 12.700 is brought into contact with solid Ca(OH)2. What is [Ca]2+ at equilibrium? The 𝐾sp of Ca(OH)2 is 1.3×10.

  • A5.2×10 M
  • B2.6×10 M
  • C6.1×10 M
  • D9.9×10 M
  • E7.9×10 M

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