객관식
Consider a buffer solution that is 0.50 M in NH3 and 0.20 M in NH4Cl. For ammonia, pKb = 4.75. Calculate the pH of 1.0 L of the solution upon the addition of 30.0 mL of 1.0 M HCl to the original buffer solution.
432
views
18. Aqueous Equilibrium
Henderson-Hasselbalch Equation
Multiple Choice
What is the pH of a buffer system that has 0.25 M HCN and 0.38 M CN⁻, given that the pKa of hydrocyanic acid is 9.23?
A
9.03
B
8.83
C
9.43
D
9.23
검증된 단계별 안내1
Identify the components of the buffer system: HCN (weak acid) and CN⁻ (conjugate base).
Use the Henderson-Hasselbalch equation to calculate the pH of the buffer: \( \text{pH} = \text{pKa} + \log \left( \frac{[\text{A}^-]}{[\text{HA}]} \right) \), where \([\text{A}^-]\) is the concentration of the conjugate base (CN⁻) and \([\text{HA}]\) is the concentration of the weak acid (HCN).
Substitute the given values into the equation: \( \text{pH} = 9.23 + \log \left( \frac{0.38}{0.25} \right) \).
Calculate the ratio \( \frac{0.38}{0.25} \) to find the value to be used in the logarithm.
Add the result of the logarithm to the pKa value (9.23) to find the pH of the buffer system.
Related Videos
Related Practice
