Given that acetic acid (CH₃COOH) has pK_a ≈ 5, the estimated pH of an aqueous 0.001 M sodium acetate (CH₃COONa) salt solution is:

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11ecba2d_11ff_6ec6_a3bf_ff9e3b5785ea_MD0008_00 Salts are formed by the neutralization reaction of an acid and a base. The conjugate acids and bases formed during neutralization are the same ions that make up the salt. Therefore, when a salt is dissolved in water, some salt ions can act as an acid or as a base and react with water to produce OH⁻ or H₃O⁺ (a hydrolysis reaction). As such, the pH of the solution will be affected. The tendency of the salt ions to act as an acid or a base depends on the strengths of the acid and the base involved in forming the salt. Strong acids form weak conjugate bases, and strong bases form weak conjugate acids. Therefore, examining the strengths of the ionic species permits a qualitative assessment of the salt solution pH: Neutral salts formed from a strong acid reacting with a strong base give neutral solutions (pH = 7). Acidic salts formed from a strong acid reacting with a weak base give acidic solutions (pH < 7). Basic salts formed from a weak acid reacting with a strong base give basic solutions (pH > 7). Salts formed from a weak acid reacting with a weak base are more difficult to broadly classify, and the solution pH of these salts often must be determined experimentally or by calculation. Although the pH of a 0.001 M CH₃COONa salt solution can be calculated, an exact solution pH is not requested; the nature of the solution can be assessed qualitatively. Considering the ions of CH₃COONa in detail, CH₃COONa is a basic salt produced by the reaction of CH₃COOH (a weak acid) with NaOH (a strong base). Therefore, CH₃COONa will undergo hydrolysis to produce a basic solution (pH > 7). (Choices A, B, and C) CH₃COONa is a basic salt and will not produce an acidic or neutral solution (pH ≤ 7) from hydrolysis. Educational objective: The pH of a salt solution is determined by the extent of hydrolysis caused by the nature of the salt. Neutral salts yield solutions with pH = 7, acidic salts give solutions with pH < 7, and basic salts produce solutions with pH > 7.

Given That Acetic Acid (CH3COOH) Has PKa ≈ 5, the Estimated

Given That Acetic Acid (CH₃COOH) Has PK_a ≈ 5, the Estimated