Question: If the pKa of acetic acid is 4.76, what is the pH of a 0.1 M solution?
Options:
4.76
5.76
6.76
3.76
Correct Answer: 4.76
Solution:
For a weak acid, pH ≈ pKa for a 0.1 M solution, so pH ≈ 4.76.
If the pKa of acetic acid is 4.76, what is the pH of a 0.1 M solution?
Practice Questions
Q1
If the pKa of acetic acid is 4.76, what is the pH of a 0.1 M solution?
4.76
5.76
6.76
3.76
Questions & Step-by-Step Solutions
If the pKa of acetic acid is 4.76, what is the pH of a 0.1 M solution?
Step 1: Understand that pKa is a measure of the strength of an acid. A lower pKa means a stronger acid.
Step 2: Recognize that acetic acid is a weak acid with a pKa of 4.76.
Step 3: Know that for weak acids, the pH can be approximated to be equal to the pKa when the concentration is not too low.
Step 4: Since the concentration of acetic acid is 0.1 M, which is not too low, we can use the approximation.
Step 5: Therefore, we can say that the pH of the 0.1 M acetic acid solution is approximately equal to the pKa, which is 4.76.
Weak Acid Equilibrium – Understanding the relationship between pKa and pH for weak acids, particularly that for dilute solutions, pH can be approximated by pKa.
Henderson-Hasselbalch Equation – Application of the Henderson-Hasselbalch equation for calculating pH in weak acid solutions.
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