The following pictures depict solutions of CaCO3, which may also contain ions ot

Question

The following pictures depict solutions of CaCO3, which may also contain ions other than Ca2+ and CO32– which are not shown. Gray spheres represent Ca2+ ions and unshaded spheres represent CO32– ions. Use these pictures to answer questions 8 and

8. If solution (1) is a saturated solution, which solution (1) – (4) represent the solution after a small amount of HNO3 is added and equilibrium is restored?

A. (1) B. (2) C. (3) D. (4) E. None of these.

9. If solution (1) is a saturated solution, which solution (1) – (4) represent the solution after a small amount of Na2CO3 is added and equilibrium is restored?

A. (1) B. (2) C. (3) D. (4) E. None of these.

10. Potassium chromate is slowly added to a solution containing 0.20 M AgNO3 and 0.20 M Ba(NO3)2. Which description best fits what occurs?

A. Potassium nitrate alone eventually precipitates.

B. Silver chromate alone eventually precipitates.

C. Silver chromate eventually precipitates, followed by barium chromate.

D. Barium chromate eventually precipitates, followed by silver chromate.

E. Nothing precipitates no matter how much potassium chromate is added.

11.Which choice best describes what occurs when equal volumes of 0.020 M Pb(NO3)2 and 0.020 M BaCl2 are combined?

A. Only Ba(NO3)2 precipitates. D. Both Ba(OH)2 and PbCl2 precipitate.

B. Only Ba(OH)2 precipitates. E. Nothing precipitates.

C. Only PbCl2 precipitates.

12. Al(OH)3 is insoluble at pH 7 but extremely soluble in a pH 13 solution. Which statement best explains this observation?

A. The common ion effect, which increases solubility, is induced at pH 13.

B. Al(OH)3 is more soluble in acidic solutions due to its basic anion.

C. A complex ion forms between Al3+ and OH– at pH 13 causing the solubility of Al(OH)3 to increase.

D. All of these explanations explain the observation.

E. None of these statements explain the observation.

Explanation / Answer

I do not see any pictures, however, I will try to answer it in the best possible way.

8. CaCO3 Ksp 5 x 10^-9

Ca(NO3)2 Ksp 7 x 0^-7

If (1) represent saturated solution,

By adding HNO3, we get the reaction,

CaCO3 + 2HNO3 = Ca(NO3)2 + H2CO3

We get the formation of Ca(NO3)2 in solution.

Since the Ksp of Ca(NO3)2 is greater then Ksp for CaCO3, that means more Ca2+ ions will be present in solution.

9. If Na2CO3 is added to thi solution.

The equilibrium will shift towards left, such that less of Ca2+ (more CaCO3) will be present in solution.

10. Ksp for Ag2CrO4 1.12 x 10^-12

Ksp for BaCrO4 1.17 x 10^-10

So when we add potassium chromate, the first salt to precipitate would be one with lowest Ksp value.

So the correct answer would be,

C. Silver chromate eventually precipitates, followed by barium chromate.

11. C. Only PbCl2 precipitates

12. At pH 7 Al(OH)3 is present whereas, at pH 13 Al(OH)4^-1 is present.

So the correct answer would be,

C. A complex ion forms between Al3+ and OH- at pH 13 causing the solubility of Al(OH)3 to increase.

Related Questions

Navigate

• Browse (All)
• Browse T
• Subjects

Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.