객관식
At the equivalence point during the titration of a weak acid with a strong base, would the pH be acidic, neutral, or basic?
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17. Acid and Base Equilibrium
pH of Weak Acids
객관식
An unknown weak acid has an initial concentration of 0.55 M. What is the pH of the solution if the weak acid also has a pKa of 5.79?
A
0.60
B
6.05
C
3.02
D
5.75
검증된 단계별 안내1
Start by understanding the relationship between pH, pKa, and the concentration of a weak acid. The pH of a weak acid solution can be calculated using the formula: \( \text{pH} = \frac{1}{2} (\text{pKa} - \log [\text{HA}]) \), where \([\text{HA}]\) is the initial concentration of the acid.
Identify the given values: the initial concentration of the weak acid \([\text{HA}]\) is 0.55 M, and the pKa of the acid is 5.79.
Substitute the given values into the formula: \( \text{pH} = \frac{1}{2} (5.79 - \log(0.55)) \).
Calculate \( \log(0.55) \) using a calculator or logarithm table. This will give you the logarithmic value needed for the formula.
Finally, compute the expression \( \frac{1}{2} (5.79 - \log(0.55)) \) to find the pH of the solution. This will give you the pH value, which is the measure of acidity of the solution.
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