Multiple Choice
A buffer solution is made by dissolving 0.780 moles of NaClO in 1.00 L of 0.560 M HClO. What is the pH of the solution after 0.140 moles of NaOH is added? The Ka of HClO is 2.9 × 10^-8.
18. Aqueous Equilibrium
Intro to Buffers
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Which component of the acetic acid buffer pair would react with added HCl?
A
Water (H2O)
B
Acetate ion (CH3COO-)
C
Acetic acid (CH3COOH)
D
Hydronium ion (H3O+)
Verified step by step guidance1
Understand that a buffer solution is composed of a weak acid and its conjugate base. In this case, the acetic acid buffer consists of acetic acid (CH3COOH) and its conjugate base, the acetate ion (CH3COO-).
Recognize that when a strong acid like HCl is added to the buffer solution, it will dissociate completely in water to form H+ ions (or H3O+ ions in aqueous solution).
Identify that the role of the buffer is to neutralize the added H+ ions to minimize changes in pH. The component of the buffer that reacts with the added H+ ions is the conjugate base, which in this case is the acetate ion (CH3COO-).
Write the chemical reaction that occurs when the acetate ion reacts with the added H+ ions: CH3COO- + H+ → CH3COOH.
Conclude that the acetate ion (CH3COO-) is the component of the acetic acid buffer that reacts with the added HCl, converting it into acetic acid (CH3COOH) and thus maintaining the pH of the solution.
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