Which of the following salts in aqueous solution will have a pH greater than 7?
Answer Details
The salt that will have a pH greater than 7 in aqueous solution is K2CO3. When a salt is dissolved in water, it may undergo hydrolysis, which is a chemical reaction between the ions of the salt and the water molecules. Depending on the nature of the ions, the hydrolysis of a salt can result in an acidic, basic or neutral solution. K2CO3 is a salt of a strong base (KOH) and a weak acid (H2CO3). When it is dissolved in water, the carbonate ions react with water molecules to produce hydroxide ions (OH-) and bicarbonate ions (HCO3-). HCO3- + H2O ⇌ H3O+ + OH- The presence of hydroxide ions in solution makes it basic. Therefore, the pH of a solution of K2CO3 in water will be greater than 7. In contrast, NaCl, ACI3, FeCI3, and Na2SO4 do not contain hydroxide ions or any other ions that can significantly affect the pH of the solution. They will therefore result in neutral solutions with a pH of 7. Therefore, the answer is K2CO3, because it is the only salt of the options given that will produce a basic solution with a pH greater than 7.