5. Consider the carbonate ion test that you might perform on a typical +2 metal

Question

5. Consider the carbonate ion test that you might perform on a typical +2 metal carbonate as an equilibrium: MH20 +CO a) Based on this equilibrium and the observed (limited) solubility of C02 in water, predict the outcome of bubbling C02 gas through solutions of each of the three +1/+ 2 cations studied in this experiment. Justify your prediction In light of your answer to part (a) of this question, explain why a solution of Zn (H20)2 (0H)4 upon treatment with C02 gas, first gives a precipitate of Znc03 then the precipitate dissolves on continued addition of CO2. Write equations for both reactions involved. Equation: Equation:

Explanation / Answer

a) For +1 cation like Na+ bubbling with CO2 gives bicarbonate as below

Na2CO3 (saturated) + H2O + CO2 = 2 NaHCO3? .

For +1 cation like Li+ bubbling with CO2 gives bicarbonate as below

Li2CO3 (solid) + H2O + CO2 ? 2LiHCO3 (solution)

For +1 cation like K+ bubbling with CO2 gives bicarbonate as below

K2CO3 (solid) + H2O + CO2 ? 2KHCO3 (solution)

For +2 cation like Ca2+ bubbling with CO2 gives bicarbonate as below

CaCO3 (s) + H2O (l) + CO2 (aq) ? Ca(HCO3)2 (aq)

b) [Zn(H2O)2(OH)4]2- upon treatment with CO2 gas, first gives a precipitate of ZnCO3

[Zn(H2O)2(OH)4]2- (aq) + CO2 (g) ? ZnCO3 (s) + 3H2O (l) + 2OH- (aq)

On continued addition of CO2 we get bicarbonate precipitate, wherein bicarbonate being unstable dissolves in solution.

ZnCO3(s) + CO2(g) + H2O(l) ? Zn(HCO3)2 (aq) (soluble)

Related Questions

Navigate

• Browse (All)
• Browse 5
• Subjects

---

---

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