Experiment 4: The synthesis of potassium aluminium sulphate

Why is the dissolution of aluminium done in the fumehood?

• Because it gives out a pungent smell

• Because it produces many gas bubbles

• Because it is explosive

What is the purpose of removing the paint from the aluminium can?

• To make the aluminium can silver

• To make sure that alum is colourless

• To remove the impurities

Identify the gas produced at the end of part A.

What is the white precipitate produced when sulphuric acid was added to the filtrate?

• alum

• aluminium sulphate

• aluminium hydroxide

Aluminium strips are cut into small pieces because

The following are correct about vacuum filter except

• It is designed to collect solid

• It is slower compared to gravity filter

• It forces air through reduced pressure

Ethanol is used to wash alum instead of water because

• alum dissolves in water

• it gives alum a shiny appearance

• poisonous substance is produced

What is the property of the white solid produced in part B?

Ethanol must be kept stoppered because

• it is flammable

• it is explosive

• it is photosensitive

Aluminium is used as