what happens when acetaldehyde is treated with fehling solution ? give the equation ?
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OXIDATION OF ALDEHYDES AND KETONES
This page looks at ways of distinguishing between aldehydes and ketones using oxidising agents such as acidified potassium dichromate(VI) solution, Tollens' reagent, Fehling's solution and Benedict's solution.
Background
Why do aldehydes and ketones behave differently?
You will remember that the difference between an aldehyde and a ketone is the presence of a hydrogen atom attached to the carbon-oxygen double bond in the aldehyde. Ketones don't have that hydrogen.

The presence of that hydrogen atom makes aldehydes very easy to oxidise. Or, put another way, they are strong reducing agents.
Because ketones don't have that particular hydrogen atom, they are resistant to oxidation. Only very strong oxidising agents like potassium manganate(VII) solution (potassium permanganate solution) oxidise ketones - and they do it in a destructive way, breaking carbon-carbon bonds.
Provided you avoid using these powerful oxidising agents, you can easily tell the difference between an aldehyde and a ketone. Aldehydes are easily oxidised by all sorts of different oxidising agents: ketones aren't.
You will find details of these reactions further down the page.
What is formed when aldehydes are oxidised?
It depends on whether the reaction is done under acidic or alkaline conditions. Under acidic conditions, the aldehyde is oxidised to a carboxylic acid. Under alkaline conditions, this couldn't form because it would react with the alkali. A salt is formed instead.
.
Building equations for the oxidation reactions
If you need to work out the equations for these reactions, the only reliable way of building them is to use electron-half-equations.
The half-equation for the oxidation of the aldehyde obviously varies depending on whether you are doing the reaction under acidic or alkaline conditions.
Under acidic conditions it is:

. . . and under alkaline conditions:

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These half-equations are then combined with the half-equations from whatever oxidising agent you are using. Examples are given in detail below.
Specific examples
In each of the following examples, we are assuming that you know that you have either an aldehyde or a ketone. There are lots of other things which could also give positive results.
This page looks at ways of distinguishing between aldehydes and ketones using oxidising agents such as acidified potassium dichromate(VI) solution, Tollens' reagent, Fehling's solution and Benedict's solution.
Background
Why do aldehydes and ketones behave differently?
You will remember that the difference between an aldehyde and a ketone is the presence of a hydrogen atom attached to the carbon-oxygen double bond in the aldehyde. Ketones don't have that hydrogen.

The presence of that hydrogen atom makes aldehydes very easy to oxidise. Or, put another way, they are strong reducing agents.
Because ketones don't have that particular hydrogen atom, they are resistant to oxidation. Only very strong oxidising agents like potassium manganate(VII) solution (potassium permanganate solution) oxidise ketones - and they do it in a destructive way, breaking carbon-carbon bonds.
Provided you avoid using these powerful oxidising agents, you can easily tell the difference between an aldehyde and a ketone. Aldehydes are easily oxidised by all sorts of different oxidising agents: ketones aren't.
You will find details of these reactions further down the page.
What is formed when aldehydes are oxidised?
It depends on whether the reaction is done under acidic or alkaline conditions. Under acidic conditions, the aldehyde is oxidised to a carboxylic acid. Under alkaline conditions, this couldn't form because it would react with the alkali. A salt is formed instead.
.
Building equations for the oxidation reactions
If you need to work out the equations for these reactions, the only reliable way of building them is to use electron-half-equations.
The half-equation for the oxidation of the aldehyde obviously varies depending on whether you are doing the reaction under acidic or alkaline conditions.
Under acidic conditions it is:

. . . and under alkaline conditions:

Use the BACK button on your browser to return to this page.
These half-equations are then combined with the half-equations from whatever oxidising agent you are using. Examples are given in detail below.
Specific examples
In each of the following examples, we are assuming that you know that you have either an aldehyde or a ketone. There are lots of other things which could also give positive results.
rupayan024:
thanks for ur help now i got to know the answer of it
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When acetaldehyde is heated with Fehling's solution, a red precipitate is formed.
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