1) Which of the following solutions is a buffer? a) 0.10 M CH3COOH and 0.10 M CH
ID: 958209 • Letter: 1
Question
1) Which of the following solutions is a buffer? a) 0.10 M CH3COOH and 0.10 M CH3COONa, (b) 0.10 M CH3COOH, (c) 0.10 M HCl and 0,10 M NaCl, (d) both a and c, (e) all of a, b, and c.
2) a) Calculate the pH of a buffer that is 0.12 M in lactic acid and 0.11 M in sodium lactate. (b) Calculate the pH of a buffer formed by mixing 85 mL of 0.13 M lactic acid with 95 mL of 0.15M sodium lactate.
3) You are asked to prepare a pH=3.00 buffer solution starting from 1.25 L of a 1.00 M solution of hydroflouric acid (HF) and any amount you need of sodium flouride (NaF). (a) What is the pH of the hydroflouric acid solution prior to adding sodium flouride? (b) How many grams of sodium benzoate should be added to prepare the buffer? Neglect the small volume change that occurs when the sodium benzoate is added.
Explanation / Answer
A buffer solution is a system that consists in a weak acid and a its conjugate base.
HCl is a strong acid (Pka = -6.3) therefore option c is discarded
Option b is not suitable because it only consists of the weak acid, the conjugated base is missing.
Since b and c are not suitable then d and e are not suitable either.
Option A is the right choice
It has the weak Acid "CH3COOH"
and the conjugated base "CH3COONa"
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