AS Paper 2 exam questions

Question 1

A student has samples of 4 compounds
- Butanoic acid
- 2-methylpropanal
- 2-methylpropanoic acid
- 2-methylpropan-1-ol
How would you identify theses compounds.

Answer 1

First do test for aldehyde, 2-methylpropanal- Fehling’s solution, a positive test should turn from blue to brick red
Next test for alcohol, 2-methylpropan-1-ol- Acidified potassium dichromate, a positive test should turn from orange to green
Use IR spectrum to distinguish between Butanoic acid and 2-methylpropanoic acid, use the fingerprint region and look for an exact match to the spectra of the known compounds