A buffer solution is made such that the initial concentrations of lactic acid (HC₃H₅O₃)and the lactate ion (C₃H₅O₃^-)are both 0.600 M.What is the resulting pH if 10.0 mL of 1.00 M hydrochloric acid is added to 0.500 L of the buffer solution? (The K_a of HC₃H₅O₃ is 1.4 $\times$ 10^-4.)

Question

Quizplus · Accepted Answer

The correct answer is A because the pH of the buffer solution will decrease when hydrochloric acid is added. The decrease in pH is due to the increase in the concentration of hydrogen ions in the solution. The K_a of HC₃H₅O₃ is 1.4 × 10^-4, which means that the acid is weak and will not completely dissociate in water. The addition of hydrochloric acid will shift the equilibrium to the left, resulting in a decrease in the concentration of lactate ions and an increase in the concentration of lactic acid. The pH of the solution will decrease as a result of the increase in the concentration of hydrogen ions.

A Buffer Solution Is Made Such That the Initial Concentrations ×\times×

A Buffer Solution Is Made Such That the Initial Concentrations $\times$