A buffer solution is 0.080 M in lactic acid (K_a = 1.8 × 10^-4) and 0.070 M in sodium lactate. The pH of the solution is A) 2.86. B) 3.68. C) 3.80. D) 4.18. E) 4.62.

Question

Quizplus · Accepted Answer

The pH of a buffer solution can be calculated using the Henderson-Hasselbalch equation: pH = pKa + log([A-]/[HA]), where [A-] is the concentration of the conjugate base (sodium lactate, 0.070 M) and [HA] is the concentration of the acid (lactic acid, 0.080 M). The pKa is the negative logarithm of the acid dissociation constant (Ka), which is given as 1.8 × 10^-4. Thus, pKa = -log(1.8 × 10^-4) ≈ 3.74. Plugging the values into the equation gives pH = 3.74 + log(0.070/0.080) ≈ 3.68.

A Buffer Solution Is 0