The correct option for the question is **C. diethyl ether**. ### Detailed Explanation When excess ethanol (C₂H₅OH) is heated to 145°C in the presence of concentrated sulfuric acid (H₂SO₄), a dehydration reaction occurs. Here’s a step-by-step breakdown of the process: 1. **Role of Concentrated H₂SO₄**: Concentrated sulfuric acid acts as a dehydrating agent. It removes water (H₂O) from the ethanol molecules, facilitating the formation of ethers. 2. **Dehydration of Ethanol**: The dehydration of ethanol can be represented by the following reaction: \[ 2 \text{C}_2\text{H}_5\text{OH} \xrightarrow{\text{H}_2\text{SO}_4} \text{C}_2\text{H}_5\text{O}\text{C}_2\text{H}_5 + \text{H}_2\text{O} \] In this reaction, two ethanol molecules lose a water molecule to form diethyl ether (C₂H₅OC₂H₅). 3. **Temperature Consideration**: The temperature of 145°C is significant because it is above the boiling point of ethanol (78.37°C) and allows for the reaction to proceed efficiently, promoting the formation of diethyl ether rather than other possible products. 4. **Formation of Diethyl Ether**: The product formed, diethyl ether, is an ether where two ethyl groups are bonded to an oxygen atom. This reaction is favored under the conditions provided (excess ethanol and concentrated sulfuric acid). ### Why Other Options Are Incorrect - **A. Ethyne**: Ethyne (C₂H₂) is an alkyne that would require a different reaction pathway, typically involving the dehydrohalogenation of a haloalkane or the elimination of water from an alcohol under different conditions. Ethanol does not convert to ethyne under the conditions described. - **B. Diethyl Sulphate**: Diethyl sulfate (C₂H₅)₂SO₄ is formed through the reaction of ethanol with sulfuric acid, but this typically requires a different stoichiometry and conditions (such as the presence of sulfur trioxide or a different reaction pathway). The reaction conditions provided favor ether formation instead. - **D. Acetone**: Acetone (C₃H₆O) is a ketone that cannot be formed from ethanol under the given conditions. Acetone is typically produced through the oxidation of isopropyl alcohol or through other synthetic routes, not from ethanol directly. ### Summary of Key Points - The reaction of ethanol with concentrated sulfuric acid at elevated temperatures leads to the formation of diethyl ether through dehydration. - Concentrated sulfuric acid acts as a dehydrating agent, facilitating the removal of water from ethanol. - The reaction conditions (excess ethanol and high temperature) favor ether formation over other possible products. - Understanding the specific reaction pathways and conditions is crucial for predicting the products of organic reactions. ### Revision Summary - **Diethyl ether is formed by the dehydration of ethanol in the presence of concentrated sulfuric acid.** - **The reaction involves the removal of water from two ethanol molecules.** - **Temperature and the presence of excess ethanol are critical for favoring ether formation.** - **Other options (ethyne, diethyl sulfate, acetone) do not result from the given reaction conditions.**