Lactic acid (CH3CH(OH)COOH\text{CH}_3\text{CH(OH)COOH}CH3CH(OH)COOH) is a weak monoprotic acid found in sour milk and produced in muscles during anaerobic respiration. An aqueous solution of lactic acid has a concentration of 0.055 mol dm-3.
At 298 K, the pKa\text{p}K_{\text{a}}pKa of lactic acid is 3.86.
What is the pH of this lactic acid solution at 298 K?
1.261.261.26
2.562.562.56
5.125.125.12
1.301.301.30