JEE Main20241 Feb 2024Morning ShiftChemistryIonic EquilibriumActual
K a for CH 3 COOH is 1 . 8 × 10 - 5 and K b for NH 4 OH is 1 . 8 × 10 - 5 . The pH of ammonium acetate solution will be
Correct answer
7
Step-by-step solution
K a of CH 3 COOH = 1 . 8 × 10 - 5 K a of NH 4 OH = 1 . 8 × 10 - 5 We know that pH of solution of the salt made up of weak acid CH 3 COOH and weak base NH 4 OH can be found using formula pH = 7 + 1 2 pK a - pK b pK a = - log K a = - log 1 . 8 × 10 - 5 = - log 1 . 8 + log 10 - 5 = - 0 . 2553 - 5 = + 4 . 7447 pK b = - log K b = - log 1 . 8 × 10 - 5 = 4 . 7447 pH = 7 + 1 2 4 . 7447 - 4 . 7447 = 7 + 0 = 7 If K a = K b , then pH of salt is always 7 . Therefore, the pH of given solution is 7 .