Consider the reaction represented by the following equation CaCI2 (aq) + H 2C2O 4(aq) ⇌ CaC 2O4(s) + 2HCI(aq). Which of the following would dissolve the pre...

Assessment: WAEC SSCE - Chemistry - 1993 (Objective) Subject: Chemistry

Question 1 Report

Consider the reaction represented by the following equation CaCI2 (aq) + H 2C2O 4(aq) ⇌ CaC 2O4(s) + 2HCI(aq). Which of the following would dissolve the precipitate of CaC 2O4 formed?
Answer Details
The formation of a precipitate in this reaction indicates that CaC 2O4 is insoluble in water. In order to dissolve the precipitate, we need to find a substance that can react with it to form a soluble compound. , adding concentrated hydrochloric acid, is the correct answer. This is because the reaction between CaC 2O4 and HCl produces soluble calcium chloride (CaCl 2) and carbon dioxide (CO 2). The balanced chemical equation for this reaction is: CaC 2O4 + 4HCl → CaCl 2 + 2CO 2 + 2H 2O The carbon dioxide gas will escape as bubbles, leaving behind a solution of CaCl 2, which is soluble in water. The other options will not dissolve the CaC 2O4 precipitate. Stirring the mixture vigorously will not change the chemical nature of the substances in the solution. Adding more calcium chloride solution will not react with the CaC 2O4 precipitate since it is already present in excess. Increasing the concentration of ethanedioic acid will not react with CaC 2O4 either, as it is a weak acid and cannot displace the strong acid HCl. Adding distilled water will not dissolve the precipitate since CaC 2O4 is insoluble in water.

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