JEE Main202431 Jan 2024Morning ShiftChemistryAlcohols Phenols and EthersActual
Given below are two statements: One is labelled as Assertion A and the other is labelled as Reason R: Assertion A: p K a value of phenol is 10 . 0 while that of ethanol is 15 . 9 . Reason R: Ethanol is stronger acid than phenol. In the light of the above statements, choose the correct answer from the options given below:
Options
- AA is true but R is false
- BA is false but R is true
- CBoth A and R are true and R is the correct explanation of A
- DBoth A and R are true but R is NOT the correct explanation of A.
Correct answer
A. A is true but R is false
Step-by-step solution
pK a is a measure of the acidity of a particular molecule. It measures the strength of an acid by how tightly a proton is held by a Bronsted acid. The lower the value of pK a , the stronger the acid and the greater its ability to donate its protons. describe the acidity of a particular molecule. pK a = - logK a Hence, Assertion is true, Phenol is more acidic than ethanol because after losing a proton H + , phenol forms phenoxide ion which is stabilised by resonance whereas ethoxide ion is not.