Chem (unit 2)- Alcohols

Question 1

Distinguishing between aldehydes using Tollen’s Reagent

Answer 1

Tollen’s Reagent= aqueous ammonia and silver nitrate solution. The silver ions are reduced to silver atoms which coat the test-tube producing a silver mirror effect.
alcohol + 2Ag+ + H20 > 2Ag +H+
Ketones= No visible change

Question 2

Distinguishing between aldehydes and ketones using Fehling’s solution

Answer 2

Fehling’s solution= copper ll ions which act as a weak oxidising agent and oxidise the aldehyde to a carboxylic acid. The copper ll ions are reduced to copper l ions which are brick-red and insoluble in water so a brick-red precipitate forms.
Ketones= No visible change