Describe two different test tube reactions to identify the following organic compounds: propanal and benzoic acid.
There are several different answers one could make and an exam question would just require one for each.
1) Propanal - from the ending "al" this is an aldehyde.
- Add Tollens' reagent. Positive result: Silver mirror formed.
- Add Fehling's / Benedict Solution. Positive result: Red precipitate formed.
- Acidified potassium dichromate. Positive result: Orange to green (due to oxidation).
2) Benzoic acid - You probably have not come across this in the lab at school. Nevertheless from the name you can work out that it is a carboxylic acid.
- Add Sodium carbonate/ Sodium hydrogen carbonate. Positive result: Effervescence is observed.
DD
Related Chemistry A Level answers
All answers ▸1.5 g of hydrocarbon undergoes complete combustion to give 4.4 g of CO2 and 2.7 g of H2O. Given this data, what is the empirical formula of this hydrocarbon?
2.11g of MgCl2 is added to 30cm3 of water. Find the concentration of chloride ions in the solution.
Excess KCN(aq) is added to a solution of [Co(H2O)6]2+. Identify the complex ion formed and predict its shape and charge.
Nitric acid (HNO3) is a strong acid. Ethanoic acid (CH3COOH) is a weak acid. Write an equation to show how ethanoic acid behaves as a weak acid in its reaction with water.