Answer to Question #315764 in General Chemistry for johnrich

Question

. Calculate the following buffer solution using the Henderson-Hasselbalch equation.

1. Calculate the pH of the buffer solution that contain 0.20 M HOCl (Ka= 4.0 x 10-8) and 0.10 M HCl.

2. What is the pH of a buffer solution that contains 0.50 M CH3CO3H (Ka = 1.8 x 10-5 ) and 0.02 M

H2CO3?

Answer 1

pH = pK_A + log₁₀ ([A^-]/[HA]) = -log₁₀K_A + log₁₀ ([A^-]/[HA])

1. pH = -log₁₀(4.0*10^-8) + log₁₀(0.2/0.1) = 7.4 + 0.3 = 7.7
2. pH = -log₁₀(1.8*10^-5) + log₁₀(0.5/0.02) = 4.7 + 1.4 = 6.1