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An acqeous solution of phenol is acidic to litmus paper whereas that of ethanol is neutral.Explain this observation

An acqeous solution of phenol is acidic to litmus paper whereas that of ethanol is neutral.Explain this observation

Grade:12th pass

5 Answers

Saurabh Koranglekar
askIITians Faculty 10335 Points
4 years ago
Dear student

Phenol is a very weak acid and the position of equilibrium lies well to the left. Phenol can lose a hydrogen ion because the phenoxide ion formed is stabilised to some extent. The negative charge on the oxygen atom is delocalised around the ring.



Regards
Arun
25750 Points
4 years ago
Phenol is a very weak acid and the position of equilibrium lies well to the left. Phenol can lose a hydrogen ion because the phenoxide ion formed is stabilised to some extent. The negative charge on the oxygen atom is delocalised around the ring.
 
Vikas TU
14149 Points
4 years ago
Dear student 
Because in aqueous solution, when phenol releases H+ion then phenoxide ring is formed which is stabilised by resonance, so it can easily donate proton and show acidic behaviour. But in case of ethanol there is no kind of resonating structures are formed. so it doesn't show any acidic behaviour in aqueous solution.
RISHIKA
550 Points
3 years ago
hello friend
Because in aqueous solution, when phenol releases H+ion then phenoxide ring is formed which is stabilised by resonance, so it can easily donate proton and show acidic behaviour. But in case of ethanol there is no kind of resonating structures are formed. so it doesn't show any acidic behaviour in aqueous solution.
thank u
Srinivasan S
27 Points
3 years ago
Hi,
 
In addition to the resonance stabilization of the phenoxide ion, there is another more important factor in play, i.e., solvation.
The bond dissociation of PhO-H ----> PhO-  + H+  ions need to be stabilized in such a way that they are no more close to each other for re-attaching to form PhOH. 
ter, being an excellent solvating agent, solvates both PhO- (x H2O) and H+ (x OH2). As solvation increases the effective size of each ion, individually both get weakened unlike free phenoxide and H+ ions, and are unable to react back to form PhOh easily.  Ethanol is a much weaker solvating as well as O-H bond dissociating agent than water. So, phenol is neutral in ethanol.
 
Hope this helps.
 

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