In section B you tested for the presence of SO₄²⁻, K⁺, Al³⁺ and H₂O. Be able to explain how they were tested for and what should have been observed in each test.
Answer: Sulfate was tested for by reacting the alum with BaCl2. A white precipitate of BaSO4 formed. K and H2O were tested for by the flame test. The flame turned purple which shows K in it and a popping noise was heard as the water evaporated. Al was tested for by reacting it with KOH and checking for the Al(OH)4 precipitate and by Al having an acidic pH.