Question

Lactic acid, CH₃CH(OH) COOH, is found in sour milk. A solution containing 1.00 g of NaCH₃CH(OH) COO in 100.0 mL of 0.0500 M CH₃CH(OH) COOH has a pH = 4.11. What is the Ka of lactic acid?
a) 1.38 x 10⁻⁴
b) 2.54 x 10⁻⁴
c) 4.11 x 10⁻⁴
d) 6.22 x 10⁻⁴