Question

What is the structure of the functional group and the condensed formula for 3,4-dimethyl heptanoic acid?

Answer 1

The ending –oic acid tells you that this is a carboxylic acid.

The functional group of a carboxylic acid is the `"COOH"` group.

Its structure is

and the carbon atom is automatically C-1.

The "heptan" part of the name tells you that the molecule contains a chain of 7 carbon atoms.

So your condensed structural formula starts with

`"C-C-C-C-C-C-COOH"`

Then you attach methyl groups to C-3 and C-4.

You write them in parentheses just after those atoms and get

`"C-C-C-C(CH"_3")C(CH"_3")-C-COOH"`

Finally, you add enough `"H"` atoms to give each `"C"` atom a total of four bonds.

The condensed structural formula is

`"CH"_3"CH"_2"CH"_2"CH(CH"_3")CH(CH"_3")CH"_2"COOH"`