Ethanol on reaction of acidified potassium dichromate form:

• A. ethane
• B. ethene
• C. ethanal
• D. ethanoic acid

When ethanol reacts with acidified potassium dichromate, the primary product formed is ethanal, which is also known as acetaldehyde. This reaction is part of an oxidation process where ethanol, a primary alcohol, is oxidized to an aldehyde. Let's break down the reaction and the reasoning behind this outcome.

The Reaction Process

In the presence of acidified potassium dichromate, ethanol undergoes oxidation. The dichromate ion (Cr2O7^2-) acts as an oxidizing agent, facilitating the conversion of ethanol (C2H5OH) into ethanal (C2H4O). This transformation can be summarized in the following steps:

• Oxidation of Ethanol: Ethanol is oxidized by losing hydrogen atoms. The hydroxyl group (-OH) is converted into a carbonyl group (C=O), resulting in the formation of ethanal.
• Color Change: During this reaction, the orange color of the dichromate ion changes to green, indicating the reduction of chromium from +6 to +3 oxidation state.

Why Not the Other Options?

Let’s clarify why the other options—ethane, ethene, and ethanoic acid—are not the products of this reaction:

• Ethane (A): This is an alkane and would not be formed through oxidation. Instead, it is a saturated hydrocarbon that does not contain functional groups that can be oxidized.
• Ethene (B): Ethene is an alkene, which is formed through dehydration (loss of water) rather than oxidation. Ethanol can be dehydrated to form ethene under specific conditions, but that is not the case here with potassium dichromate.
• Ethanoic Acid (D): While ethanal can further oxidize to form ethanoic acid (acetic acid), this reaction typically requires more vigorous conditions or a longer reaction time. In the context of the question, the immediate product of ethanol oxidation is ethanal.

Summary of the Reaction

In summary, when ethanol is treated with acidified potassium dichromate, the primary product formed is ethanal (C2H4O). This reaction exemplifies the oxidation of a primary alcohol to an aldehyde, showcasing the role of dichromate as a powerful oxidizing agent. Understanding these reactions is crucial in organic chemistry, as they form the basis for many synthetic pathways and transformations.