Multiple Choice
The pH of a solution containing HIO3 (Ka = 1.7 × 10⁻¹) and KIO3 is 1.00. If the molarity of HIO3 is 0.025 M, what is the molarity of KIO3?
17. Acid and Base Equilibrium
pH of Weak Acids
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What is the pH of a buffer solution after adding 0.150 mol of HCl, assuming no volume change?
A
4.75
B
5.00
C
4.25
D
3.50
Verified step by step guidance1
Identify the components of the buffer solution, typically a weak acid and its conjugate base, and note their initial concentrations.
Use the Henderson-Hasselbalch equation: \( \text{pH} = \text{pK}_a + \log \left( \frac{[\text{A}^-]}{[\text{HA}]} \right) \), where \([\text{A}^-]\) is the concentration of the conjugate base and \([\text{HA}]\) is the concentration of the weak acid.
Calculate the change in moles of the weak acid and conjugate base after adding 0.150 mol of HCl. HCl will react with the conjugate base, decreasing its amount and increasing the amount of the weak acid.
Adjust the concentrations of the weak acid and conjugate base in the buffer solution based on the stoichiometry of the reaction with HCl.
Substitute the adjusted concentrations into the Henderson-Hasselbalch equation to find the new pH of the buffer solution.
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