Question

How do you find the elemental composition of carbon, hydrogen, and oxygen, of acetic acid?

Answer 1

We divide the mass of carbon by the mass of the molecule, and multiply by `100%`.........

Explanation:

For `H_3C-CH_2OH`:

`"% carbon"=(2xx12.011*g*mol^-1)/(46.07*g*mol^-1)xx100%=52.1%`

`"% hydrogen"=(6xx1.00794*g*mol^-1)/(46.07*g*mol^-1)xx100%=13.1%`

`"% oxygen"=(1xx15.999*g*mol^-1)/(46.07*g*mol^-1)xx100%=34.7%`

Now `%C` and `%H` COULD be measured......(an analyst generally would not touch a liquid!). Oxygen content is a harder proposition, and generally when perform microanalysis on an organic sample we report `%C`, `%H`, and `%N`, the balance, i.e. the missing percentage that makes the sum of the other percentages `100%` is assumed to be due to oxygen.