Which of the following represents the structure of the product formed when $C_2{H}_4$ reacts with water in the presence of an acid catalyst?

• A. $C_2{H}_4$ (ethylene, unchanged)
• B. $C_2{H}_{4}O2$ (acetic acid)
• C. $C_2{H}_6$ (ethane)
• D. $C_2{H}_{5}OH$ (ethanol)

Answer: (D)

Verified step by step guidance

1. Identify the starting material: ethylene, which has the formula \(\mathrm{C_2H_4}\) and contains a carbon-carbon double bond (an alkene).
2. Understand the reaction conditions: water (\(\mathrm{H_2O}\)) in the presence of an acid catalyst. This typically leads to an acid-catalyzed hydration of the alkene.
3. Recall the mechanism of acid-catalyzed hydration of alkenes: the double bond is protonated to form a carbocation intermediate, followed by nucleophilic attack by water, and finally deprotonation to give an alcohol.
4. Determine the product by adding an -OH group to one of the carbons of the original double bond and a hydrogen to the other carbon, converting the alkene into an alcohol with the formula \(\mathrm{C_2H_5OH}\) (ethanol).
5. Confirm that the product is ethanol, not ethane (\(\mathrm{C_2H_6}\)), acetic acid (\(\mathrm{C_2H_4O_2}\)), or unchanged ethylene (\(\mathrm{C_2H_4}\)).