Question

Q6.The manufacturer supplying concentrated ethanoic acid for the production of vinegar als

supplied other acids. The label had come off a batch of one of these other acids.
A sample of this unknown acid was analysed and found to contain 54.5% of carbon and 9.10% OL
hydrogen by mass, the remainder being oxygen.
CHO
(a)
Use these data to calculate the empirical formula of the unknown acid.
Show your working.

Answer 1

The problem gives us the percentages for carbon and hydrogen in the unknown acid:

54.5 % carbon

9.10 % hydrogen

The difference until 100 % is oxygen:

36.4 % oxygen

Now we may calculate the empirical formula of the unknown acid:

First we divide each percentage by the atomic mass of each component:

carbon = 54.5 / 12 = 4.54

hydrogen = 9.1 / 1 = 9.1

oxygen = 36.4 / 16 = 2.28

Now we divide the answers to the smallest number, which is 2.28:

carbon = 4.54 / 2.28 = 2

hydrogen = 9.1 / 2.28 = 4

oxygen = 2.28 / 2.28 = 1

Now the empirical formula for the acid will be:

C₂H₄O₁

And molecular formula:

(C₂H₄O₁)ₓ , but here we do not have enough information to determine unknown "x".