Vinegar is an aqueous solution of acetic acid, $H_{3}C{O}_{2}H$. Which added solute would best create a buffer that resists pH changes in vinegar?

• A. Sodium chloride, $\mathrm{Na}Cl$
• B. Sodium acetate, ${\mathrm{Na}}_{\mathrm{+}}{H}_{3}C{O}_2$
• C. Glucose, $C_6{H}_{12}{O}_6$
• D. Sodium hydroxide, $\mathrm{Na}OH$

Answer: (B)

Verified step by step guidance

1. Understand that a buffer solution is made by combining a weak acid and its conjugate base, which helps resist changes in pH when small amounts of acid or base are added.
2. Identify that vinegar contains acetic acid, which is a weak acid with the formula \(\mathrm{H_3C O_2 H}\) (or \(\mathrm{CH_3COOH}\)).
3. Recognize that to create a buffer with acetic acid, you need to add its conjugate base, which is the acetate ion \(\mathrm{CH_3COO^-}\), commonly provided by sodium acetate \(\mathrm{Na^+ CH_3COO^-}\).
4. Evaluate the other options: sodium chloride (\(\mathrm{NaCl}\)) is a neutral salt and does not provide the conjugate base; glucose (\(\mathrm{C_6H_{12}O_6}\)) is a neutral molecule and does not affect pH buffering; sodium hydroxide (\(\mathrm{NaOH}\)) is a strong base and would neutralize the acid rather than form a buffer.
5. Conclude that adding sodium acetate to vinegar provides both the weak acid (acetic acid) and its conjugate base (acetate ion), thus forming an effective buffer solution that resists pH changes.