The molecular formula of ethylbutanoate is?

Step 1: Analyze the question We need the formula of ethyl butanoate. Esters are named as alkyl alkanoate:

• The first word (ethyl) comes from the alcohol part.
• The second word (butanoate) comes from the carboxylic acid part.

Step 2: Build the formula

• Butanoic acid is C₃H₇COOH (4 carbons in total, including the carboxyl carbon).
• When it forms an ester, the H of –COOH is replaced by the alkyl group, here ethyl (C₂H₅).
• So the ester is C₃H₇COO–C₂H₅, written as C₃H₇COOC₂H₅.

This comes from the reaction: C₃H₇COOH + C₂H₅OH → C₃H₇COOC₂H₅ + H₂O

The total molecular formula is C₆H₁₂O₂.

Step 3: Check the options

• A. CH5COOC26: not a valid formula.
• B. C3HCOOC2H7: C₂H₇ is not a valid alkyl group.
• C. C₃H₇COOC₃H₇: this is propyl butanoate.
• D. C₃H₇COOC₄H₉: this is butyl butanoate.
• E. C₃H₇COOC₂H₅: this is ethyl butanoate. ✔

Answer: E

Tip: In an ester name, the first word is the alcohol's alkyl group and the second word is the acid part. Remember that "ethyl ethanoate" is CH₃COOC₂H₅. Just swap in the acid chain and the alkyl group for the ester you need.