Problem 79 - Chemistry: An Atoms-Focused Approach

Question

Which of the following salts produces an acidic solution in water: ammonium acetate, ammonium nitrate, or sodium formate?

Step-by-Step Solution

Answer

Answer: Ammonium acetate and ammonium nitrate.

Step 1: Analyze ammonium acetate

Ammonium acetate has the formula NH4CH3COO. The cation is NH4+ (ammonium), and the anion is CH3COO- (acetate). When dissolved in water, the ammonium ion will undergo hydrolysis: NH4+ + H2O -> NH3 + H3O+ As a result, the ammonium cation forms hydronium ions (H3O+), making the solution acidic. The acetate ion will also undergo hydrolysis: CH3COO- + H2O -> CH3COOH + OH- The acetate anion forms hydroxide ions (OH-), making the solution basic. However, the basicity of acetate is weaker than the acidity of ammonium. Therefore, the net result is an acidic solution.

Step 2: Analyze ammonium nitrate

Ammonium nitrate has the formula NH4NO3. The cation is NH4+ (ammonium), and the anion is NO3- (nitrate). Similar to the previous case, the ammonium cation forms hydronium ions (H3O+), making the solution acidic. The nitrate ion does not undergo hydrolysis in water because it is the conjugate base of a strong acid (HNO3). Therefore, it does not have any significant effect on the pH of the solution. The net result is again an acidic solution due to the presence of ammonium ions.

Step 3: Analyze sodium formate

Sodium formate has the formula HCOONa. The cation is Na+ (sodium), and the anion is HCOO- (formate). The sodium ion does not undergo hydrolysis in water because it is the conjugate acid of a strong base (NaOH). Therefore, it does not have a significant effect on the pH of the solution. The formate ion will undergo hydrolysis: HCOO- + H2O -> HCOOH + OH- The formate anion forms hydroxide ions (OH-), making the solution basic. The net result is a basic solution due to the presence of formate ions. #Conclusion# Out of the three salts, ammonium acetate and ammonium nitrate produce acidic solutions in water. Sodium formate forms a basic solution in water and does not meet the requirement.