This document discusses how to write molecular formulas for alcohols and carboxylic acids. It provides the general formulas, examples for propanol and butanol, and practice problems for writing formulas for butanol, hexanol, butanoic acid and propanoic acid.

1. Writing molecular formula
for Alcohols and
Carboxylic Acids

2. Alcohols
• Alcohols have the general formula CnH2n+1OH
• Example: propanol ( C3H5OH)
By using the general formula we
know that a compound with 3C’s
would have 7 hydrogens. We also
know the compound’s molecular
formula ends in OH

3. Practice
• Using the general formula of alcohols, write the molecular formula of
1. Butanol-4 carbons
2. Hexanol-6 carbons

4. Carboxylic acids
• Carboxylic acids have the general formula CnH2n+1COOH
In carboxylic acids the CnH2n+1COOH
accounts for one of the carbon atoms and
one of the hydrogen atoms.
So in writing molecular formula we must
remember to deduct one carbon and
Hydrogen from the root formula
CnH2n+1COOH
Writing the molecular formula for a
carboxylic acid with 3 Carbons
C2H5COOH

5. Practice
• Using the general formula of carboxylic acids, write the molecular formula
of;
1. Butanoic acid-4 carbons
2. Propanoic acid-5 carbons