Question
Find the pH of a solution formed by mixing equal volume of solution of 0.1 M sodium propionate and 0.1 molar propionic acid. (Given The dissociation constant of propionic acid is 1.3 10^ -5 )
MHT CET
Chemistry
Ionic Equilibrium
2026
MHT CET 2026 (13 April Shift 2)
MHT CET Chemistry Question (2026) — Solution
Options
- A. 2.45
- B. 4.89
- C. 5.98
- D. 6.89
Answer
B. 4.89
Step-by-step solution
The mixture of propionic acid and sodium propionate forms an acidic buffer. Using the Henderson-Hasselbalch equation: pH = p K_a + ( [ Salt ] [ Acid ] ) Since equal volumes of 0.1 M solutions are mixed, the concentrations of the salt and the acid in the final mixture are equal. pH = p K_a + (1) pH = p K_a = - (K_a) pH = - (1.3 10^ -5 ) pH = 5 - (1.3) pH = 5 - 0.1139 = 4.8861 4.89
Related: Chemistry — Ionic Equilibrium · All PYQ Banks