Question

Acetaldehyde is reduced with hydrogen in the presence of nickel. What is the compound formed?

Answer 1

Here it is written that acetaldehyde is reduced with hydrogen which clearly indicates that reduction is taking place. So, in order to answer this question, we should know about the oxidation and reduction of a reaction.

Complete Step By Step Answer:
Let us understand this question in complete detail.
First, let’s know about oxidation and reduction. Oxidation and reduction can be defined in terms of transfer of electrons, transfer of hydrogen and also in terms of transfer of oxygen.
For this question, we will apply the concept of reduction in terms of transfer of hydrogen.
We know that,
Oxidation and reduction with respect to oxygen transfer.
Oxidation is the gain of oxygen whereas reduction is the loss of oxygen.
Oxidation and reduction with respect to hydrogen transfer. This is exactly the opposite as in case of oxygen.
Oxidation is the loss of hydrogen whereas reduction is the gain of hydrogen.
According to this question, when acetaldehyde with chemical formula $C{H_3}CHO$ is reduced with hydrogen in the presence of nickel, we get ethanol with chemical formula $C{H_3} - C{H_2} - OH$ . The aldehyde functional group is reduced to the alcohol functional group.

Note:
It must be noted that in the above question, reduction takes place by the gain of hydrogen and loss of oxygen. Ethyl alcohol or ethanol contains more hydrogen atoms than acetaldehyde. Also, it contains one oxygen atom less than acetaldehyde as in case of acetaldehyde, carbon is attached with oxygen with double bond whereas in ethyl alcohol, carbon is attached to $- OH$ through a single bond.