Nagwa uses cookies to ensure you get the best experience on our website. Learn more about our Privacy Policy.

Lesson: Controlling Precipitation with Common Ions

Worksheet • 15 Questions

Q1:

Does silver chloride precipitate when equal volumes of a 2 . 0 × 1 0 4 M solution of A g N O 3 and a 2 . 0 × 1 0 4 M solution of N a C l are mixed? The solution also contains N a + and N O 3 ions, but sodium nitrate is very soluble and does not form a precipitate. 𝐾 s p for A g C l is 1 . 6 × 1 0 1 0 .

  • AYes: the reaction quotient, 𝑄 , is greater than 𝐾 s p , shifting the equilibrium position in favor of solid silver chloride.
  • BYes: the reaction quotient, 𝑄 , is less than 𝐾 s p , shifting the equilibrium position in favor of solid silver chloride.
  • CNo: the reaction quotient, 𝑄 , is greater than 𝐾 s p , shifting the equilibrium position in favor of the dissolved ions.
  • DNo: the reaction quotient, 𝑄 , is less than 𝐾 s p , shifting the equilibrium position in favor of the dissolved ions.
  • ENo: the reaction quotient, 𝑄 , is equal to 𝐾 s p , so the position of equilibrium does not shift in either direction.

Q2:

A 0.800 L sample of a 2 . 8 × 1 0 4 M B a ( N O ) 3 2 solution is added to 0.200 L of 4 . 8 × 1 0 4 M L i S O 2 4 . Does B a S O 4 precipitate? The 𝐾 s p of B a S O 4 is 2 . 3 × 1 0 8 .

  • AYes, the concentrations of S O 4 2 and B a 2 + are high enough: 𝑄 > 𝐾 s p .
  • BNo, the concentrations of S O 4 2 and B a 2 + are not high enough: 𝑄 < 𝐾 s p .
  • CYes, the concentrations of S O 4 2 and B a 2 + just high enough to enable precipitation: 𝑄 = 𝐾 s p .

Q3:

Silver chloride, A g C l , has a very low solubility in water: Adding ammonia significantly increases the solubility of A g C l because a complex ion is formed:

What mass of N H 3 is required to prepare 1.00 L of a solution that will dissolve 2.00 g of A g C l by formation of [ A g ( N H ) ] 3 2 + ?

Q4:

What [ A g ] + is required to reduce [ C O ] 3 2 to 2 . 8 × 1 0 M by precipitation of A g C O 2 3 ? The 𝐾 s p of A g C O 2 3 is 8 . 1 × 1 0 .

  • A 1 . 7 × 1 0 M
  • B 4 . 0 × 1 0 M
  • C 2 . 9 × 1 0 M
  • D 6 . 6 × 1 0 M
  • E 4 . 8 × 1 0 M

Q5:

Unexposed silver halides are removed from photographic film when they react with sodium thiosulfate ( N a S O ) 2 2 3 to form the complex ion [ A g ( S O ) ] . 2 3 2 3 What mass of N a S O 2 2 3 is required to prepare 1.00 L of a solution that will dissolve 1.00 g of A g B r by the formation of A g ( S O ) 2 3 2 3 ?

Q6:

About 50% of kidney stones consist of calcium phosphate, C a ( P O ) 3 4 2 . The typical mass of C a 2 + excreted in urine is 0.10 g per day. The typical amount of urine passed is 1.4 L per day. What is the maximum concentration of phosphate ions that urine can contain before a kidney stone begins to form? The 𝐾 s p of C a ( P O ) 3 4 2 is 1 . 3 × 1 0 3 2 .

  • A 1 . 5 × 1 0 1 2 M
  • B 9 . 1 × 1 0 1 3 M
  • C 1 . 7 × 1 0 1 0 M
  • D 7 . 3 × 1 0 3 0 M
  • E 2 . 3 × 1 0 2 3 M

Q7:

What is the concentration of F required to begin precipitation of C a F 2 in a solution with a C a 2 + concentration of 0.015 M? The 𝐾 s p of C a F 2 is 4 . 0 × 1 0 1 1 .

  • A 5 . 2 × 1 0 5 M
  • B 1 . 9 × 1 0 2 M
  • C 3 . 3 × 1 0 1 0 M
  • D 7 . 1 × 1 0 6 M
  • E 2 . 7 × 1 0 9 M

Q8:

The concentration of Z n 2 + ions in a 0.10 M aqueous H S 2 solution is 0.050 M. What is the minimum concentration of H O 3 + ions required to prevent the precipitation of Z n S ?

Q9:

What [ F ] is required to reduce [ C a ] 2 + to 1 . 0 × 1 0 M by precipitation of C a F 2 ? The 𝐾 s p of C a F 2 is 4 . 0 × 1 0 .

  • A 6 . 3 × 1 0 M
  • B 5 . 1 × 1 0 M
  • C 4 . 0 × 1 0 M
  • D 4 . 0 × 1 0 M
  • E 4 . 0 × 1 0 M

Q10:

Will K C l O 4 precipitate when 20 mL of a 0.050 M solution of K + is added to 80 mL of a 0.50 M solution of C l O 4 ? 𝐾 s p for K C l O 4 is 1 . 0 5 × 1 0 2 .

  • ANo: the reaction quotient, 𝑄 , is less than 𝐾 s p , shifting the equilibrium position in favor of the dissolved ions.
  • BNo: the reaction quotient, 𝑄 , is equal to 𝐾 s p , so the position of equilibrium does not shift in either direction.
  • CNo: the reaction quotient, 𝑄 , is greater than 𝐾 s p , shifting the equilibrium position in favor of the dissolved ions.
  • DYes: the reaction quotient, 𝑄 , is greater than 𝐾 s p , shifting the equilibrium position in favor of solid K C l O 4 .
  • EYes: the reaction quotient, 𝑄 , is less than 𝐾 s p , shifting the equilibrium position in favor of solid K C l O 4 .

Q11:

A solution contains 0.20 M of both P b 2 + and A g + ions. If C l ions are added to the solution, what is the concentration of A g + ions when P b C l 2 begins to precipitate? The 𝐾 s p of P b C l 2 is 1 . 6 × 1 0 5 and that of A g C l is 1 . 6 × 1 0 1 0 .

  • A 1 . 8 × 1 0 8 M
  • B 7 . 1 × 1 0 7 M
  • C 1 . 6 × 1 0 5 M
  • D 5 . 1 × 1 0 6 M
  • E 1 . 0 × 1 0 1 0 M

Q12:

What is the concentration of A g + required to begin precipitation of A g C O 2 3 in a solution that is 2 . 5 0 × 1 0 6 M in C O 3 2 ? The 𝐾 s p of A g C O 2 3 is 8 . 1 × 1 0 1 2 .

  • A 1 . 8 × 1 0 3 M
  • B 7 . 8 × 1 0 2 M
  • C 3 . 2 × 1 0 6 M
  • D 4 . 6 × 1 0 2 M
  • E 1.3 M

Q13:

C a H P O 4 has a solubility product of 7 × 1 0 7 . Will calcium hydrogen phosphate precipitate from a solution with [ C a ] 2 + = 0.0001 M and [ H P O ] 4 2 = 0.001 M?

  • ANo: the reaction quotient, 𝑄 , is less than 𝐾 s p , shifting the equilibrium position in favor of the dissolved ions.
  • BNo: the reaction quotient, 𝑄 , is equal to 𝐾 s p , so the position of equilibrium does not shift in either direction.
  • CYes: the reaction quotient, 𝑄 , is greater than 𝐾 s p , shifting the equilibrium position in favor of the dissolved ions.
  • DYes: the reaction quotient, 𝑄 , is greater than 𝐾 s p , shifting the equilibrium position in favor of solid calcium hydrogen phosphate.
  • ECalcium hydrogen phosphate is too insoluble for a solution to form.

Q14:

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 lime, C a ( O H ) 2 , a readily available inexpensive source of O H ions: The concentration of M g ( ) 2 + a q in sea water is 0.0537 M. Will M g ( O H ) 2 precipitate when enough C a ( O H ) 2 is added to give a hydroxide ion concentration of 0.0010 M?

  • AYes: the reaction quotient, 𝑄 , is greater than 𝐾 s p , shifting the equilibrium position in favor of solid M g ( O H ) 2 .
  • BNo: the reaction quotient, 𝑄 , is less than 𝐾 s p , shifting the equilibrium position in favor of the dissolved ions.
  • CNo: the reaction quotient, 𝑄 , is greater than 𝐾 s p , shifting the equilibrium position in favor of solid M g ( O H ) 2 .
  • DYes: the reaction quotient, 𝑄 , is less than 𝐾 s p , shifting the equilibrium position in favor of solid M g ( O H ) . 2
  • ENo: the reaction quotient, 𝑄 , is greater than 𝐾 s p , shifting the equilibrium position in favor of the dissolved ions.

Q15:

The concentration of M g 2 + ions in a 0.10 M aqueous ammonia solution is 0.10 M. What is the minimum concentration of ammonium ions required to prevent the precipitation of M g ( O H ) 2 ?

Preview