Multiple Choice
What is the pH of a solution made by mixing 30.00 mL of 0.10 M acetic acid with 30.00 mL of 0.10 M KOH? Assume that the volumes of the solutions are additive. Ka = 1.8 × 10^-5 for CH3CO2H.
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17. Acid and Base Equilibrium
pH of Weak Acids
Multiple Choice
What is the percent dissociation of glycine if the solution has a pH of 8.60 and a pKa of 9.60?
A
10%
B
90%
C
1%
D
50%
Verified step by step guidance1
Understand that percent dissociation refers to the fraction of the acid that dissociates into its ions in solution, expressed as a percentage.
Use the Henderson-Hasselbalch equation to relate pH, pKa, and the ratio of the concentrations of the dissociated (A-) and undissociated (HA) forms: \( \text{pH} = \text{pKa} + \log \left( \frac{[A^-]}{[HA]} \right) \).
Substitute the given values into the Henderson-Hasselbalch equation: \( 8.60 = 9.60 + \log \left( \frac{[A^-]}{[HA]} \right) \).
Solve for the ratio \( \frac{[A^-]}{[HA]} \) by rearranging the equation: \( \log \left( \frac{[A^-]}{[HA]} \right) = 8.60 - 9.60 \).
Calculate the percent dissociation using the formula: \( \text{Percent dissociation} = \left( \frac{[A^-]}{[HA] + [A^-]} \right) \times 100 \% \).
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