Water and fertilisers

Learning objectives

Describe the chemical tests for water using anhydrous cobalt(II) chloride (blue to pink) and anhydrous copper(II) sulfate (white to blue), test the purity of water using its melting and boiling points, and explain why distilled rather than tap water is used in the laboratory

State the substances that may be present in water from natural sources (dissolved oxygen, metal compounds, plastics, sewage, harmful microbes, nitrates from fertilisers and phosphates from fertilisers and detergents) and distinguish those that are beneficial from those that are potentially harmful

Describe the treatment of the domestic water supply: sedimentation and filtration to remove solids, carbon to remove tastes and odours, and chlorination to kill microbes

State that ammonium salts and nitrates are used as fertilisers, and describe the use of NPK fertilisers to supply nitrogen, phosphorus and potassium for improved plant growth and crop yields