JEE Main 2023ChemistryIonic EquilibriumHardNumerical

JEE Main 2023 — Ionic Equilibrium Question with Solution

JEE Main 2023 (24 Jan Shift 1)

Question

The dissociation constant of acetic is x × 10–5 . When 25 mL of 0.2 M CH3COONa solution is mixed with 25 mL of 0.02 M CH3COOH solution, the pH of the resultant solution is found to be equal to 5. The value of x is _______.

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Show full solutionCorrect answer: 10
Correct answer
10

Step-by-step explanation

The Henderson equation for the given acidic buffer can be written as 

pH=pKa+logsaltweak acid

5=pKa+log25×0.225×0.02⇒pKa=4⇒Ka=10-4=10×10-5

Hence, the value of x is 10.

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About this question

This is a previous-year question from JEE Main 2023, covering the Ionic Equilibrium chapter of Chemistry. PrepSharp catalogues every PYQ from JEE Main with a verified answer key and step-by-step solution prepared by IIT alumni — so you can search by chapter, topic or year and revise efficiently.