How would you calculate the empirical formula of acetic acid (CH3COOH)?

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Answer 1 · 2015-11-12T01:38:27

You would divide the numbers of each atom in the molecular formula by their highest common factor.

The empirical formula is the simplest possible formula for a compound.

The subscripts of the elements in the empirical formula must be in the smallest possible ratio.

We can write the molecular formula ${CH}_{3} COOH$ $"CH"_3"COOH"$ as $C_{2} H_{4} O_{2}$ $"C"_2"H"_4"O"_2$ .

The ratios of $C:H:O$ $"C:H:O"$ are $2 : 4 : 2$ $2:4:2$ .

The highest common factor of $2$ $2$ and $4$ $4$ is $2$ $2$ .

We can divide each of these numbers by $2$ $2$ to get the ratio

$C:H:O = 1 : 2 : 1$ $"C:H:O" = 1:2:1$

The empirical formula of acetic acid is then ${CH}_{2} O$ $"CH"_2"O"$ .