What type of reaction converts ethanol to ethene?

• A. Addition reaction
• B. Cracking reaction
• C. Dehydration reaction
• D. Substitution reaction

Answer: (C)

Removing water from an alcohol to form an alkene is dehydration. In ethanol, CH3-CH2-OH, a water molecule is removed (the OH and an H from the adjacent carbon) to give CH2=CH2, ethene. This process typically uses an acid catalyst and heat. That’s why this reaction is called dehydration. The other options describe different types of changes: an addition would add atoms across a double bond that isn’t formed yet, cracking breaks larger molecules into smaller ones, and substitution replaces an atom with another. So dehydration best explains how ethanol becomes ethene.