Part (e): Which of these solutes would you use to prepare a solution with a pH of 5.50 by dissolving the appropriate amount of a solute in water with pH=7.00?

Question

Asked on May 18, 2026Chemistry

This chemistry question involves key chemical concepts and calculations. The detailed solution below walks through each step, from identifying the reaction type to computing the final answer.

Accepted Answer · 2026-05-18T12:42:00.511Z

Here's the solution for part (e). Part (e): Which of these solutes would you use to prepare a solution with a pH of 5.50 by dissolving the appropriate amount of a solute in water with pH=7.00? The target pH is 5.50, which is acidic (less than 7.00). This means we need to add an acidic substance to the water. Step 1: Evaluate option (a) 15M NH_3. Ammonia (NH_3) is a weak base. Dissolving it in water would increase the pH above 7.00, making the solution basic. This is contrary to the goal of achieving a pH of 5.50. Therefore, option (a) is eliminated. Step 2: Evaluate option (b) 12M HCl(aq). Hydrochloric acid (HCl) is a strong acid. It would certainly decrease the pH. However, 12M HCl is an extremely concentrated acid. To achieve a pH of 5.50, it would require a very precise and significant dilution, which might not be implied by "dissolving the appropriate amount" for direct preparation. While technically possible with dilution, it's not the most direct or practical choice among the given options for this specific pH. Step 3: Evaluate option (c) NH_4Cl with hydronium ion concentration at equilibrium = 2.8 × 10^-6 M. Ammonium chloride (NH_4Cl) is a salt formed from a weak base (NH_3) and a strong acid (HCl). When dissolved in water, the ammonium ion (NH_4^+) acts as a weak acid, hydrolyzing water to produce hydronium ions (H_3O^+), thus making the solution acidic. The given hydronium ion concentration is [H_3O^+] = 2.8 × 10^-6 M. We can calculate the pH for this solution: pH = -[H_3O^+] pH = -(2.8 × 10^-6) pH ≈ 5.55 This pH (5.55) is very close to the target pH of 5.50. This means that dissolving NH_4Cl in water can directly yield a solution with a pH very near the desired value. Step 4: Conclude the best choice. Based on the elimination process and the direct calculation, NH_4Cl is the most appropriate solute. The correct solute to use is (c) NH_4Cl. That's 3 down. 2 left today — send the next one.

Accepted Answer · 2026-05-18T12:42:00.511Z

Here's the solution for part (e). Part (e): Which of these solutes would you use to prepare a solution with a pH of 5.50 by dissolving the appropriate amount of a solute in water with pH=7.00? The target pH is 5.50, which is acidic (less than 7.00). This means we need to add an acidic substance to the water. Step 1: Evaluate option (a) 15M NH_3. Ammonia (NH_3) is a weak base. Dissolving it in water would increase the pH above 7.00, making the solution basic. This is contrary to the goal of achieving a pH of 5.50. Therefore, option (a) is eliminated. Step 2: Evaluate option (b) 12M HCl(aq). Hydrochloric acid (HCl) is a strong acid. It would certainly decrease the pH. However, 12M HCl is an extremely concentrated acid. To achieve a pH of 5.50, it would require a very precise and significant dilution, which might not be implied by "dissolving the appropriate amount" for direct preparation. While technically possible with dilution, it's not the most direct or practical choice among the given options for this specific pH. Step 3: Evaluate option (c) NH_4Cl with hydronium ion concentration at equilibrium = 2.8 × 10^-6 M. Ammonium chloride (NH_4Cl) is a salt formed from a weak base (NH_3) and a strong acid (HCl). When dissolved in water, the ammonium ion (NH_4^+) acts as a weak acid, hydrolyzing water to produce hydronium ions (H_3O^+), thus making the solution acidic. The given hydronium ion concentration is [H_3O^+] = 2.8 × 10^-6 M. We can calculate the pH for this solution: pH = -[H_3O^+] pH = -(2.8 × 10^-6) pH ≈ 5.55 This pH (5.55) is very close to the target pH of 5.50. This means that dissolving NH_4Cl in water can directly yield a solution with a pH very near the desired value. Step 4: Conclude the best choice. Based on the elimination process and the direct calculation, NH_4Cl is the most appropriate solute. The correct solute to use is (c) NH_4Cl. That's 3 down. 2 left today — send the next one.

Part (e): Which of these solutes would you use to prepare a solution with a pH of 5.50 by dissolving the appropriate amount of a solute in water with pH=7.00?