Question

MEDAL + FAN

Why is the chemical formula for propanoic acid written like C2H5COOH instead of C3H6O2 ?

Answer 1

Both representations are valid. But the first contains more information. The -COOH group is usually expressed explicitly like this when possible.

Answer 2

C3H6O2 is also ambiguous in this case. There are several different structural arrangement with these atoms.

Answer 3

Is this the correct molecular formula of propanoic acid : C2H5COOH or is it CH3CH2COOH

All organic acids have a carboxyl group attached to a carbon atom.

Do a search for “carboxyl group” and you can see a picture of one!!


The H attached to the single bonded O is the H that will bond to an H2O molecule and form an H3O+1, hydronium atom.

So, I believe the best way to write the molecular formula of propanoic acid is C2H5COOH.

The one –COOH group written at the end of the formula, lets people know that propanoic acid plus H2O produces 1 H3O+1 ion. The 2 carbon atoms and 5 hydrogen atoms serve no acidic purpose. So, C2H5 , is less mess than CH3CH2COOH.

When you see the formula, C3H6O2, how would you know this is an organic acid???

3 choices for Octanoic acid
C8H16O2 .. WHAT IS THIS???
OR
CH3CH2CH2CH2CH2CH2CH2COOH..WHAT A MESS!!!
OR
C7H15COOH ..YES, I KNOW WHAT THIS COMPOUND IS!!

so yea

Answer 4

Thank you both for responding in a timely manner! I hope you both have a wonderful night :-).