# Question #1c929

##### 1 Answer

#### Answer:

I will explain how to work out the answer, rather than tell you what it is...

#### Explanation:

Take the percentage compositions by mass (think of them as masses of elements in 100g of compound) i.e. 40.57 g of carbon, 8.57g of hydrogen etc. in 100g of compound.

Divide each by the RAM to get the ratio C:H:N:O (e.g. C = 40.57/12).

Simplify the ratio by dividing all numbers by the smallest.

You may then need to scale the ratio up by a small integer (2,3, etc.) to get whole numbers throughout.

This is then your empirical formula (the formula with the simplest ratio).

The molecular formula will be a simple multiple (twice, three times etc) of the empirical formula - divide the molar mass by the RFM of the empirical formula to find out the multiple.

Apply this multiple to the empirical formula to get the formula of the compound. Presto!

Get back to me of you are not able to work it out from this...