2.37 Describe tests for the following cations:

i) FLAME TESTS

• Li+ (Lithium) burns with a red flame
• Na+ (Sodium) burns with a strong orange flame (sometimes it is so strong it can mask other colours)
• K+ (Potassium) lilac flame
• Ca2+ (Calcium) burns with a brick red flame

ii) NH4+ USING SODIUM HYDROXIDE SOLUTION (& identifying the ammonia produced)

• ammonium ions + hydroxide ions > ammonia + water
• (NH4 + OH > NH3 + H2O)
• How to test for ammonia: 
• ammonia will turn red litmus paper blue
• it also has a 'pungent' smell

iii) USING SODIUM HYDROXIDE SOLUTION (CU2+, FE2+, FE3+)

• Copper (ii) sulphate + sodium hydroxide > blue precipitate
• CuSO4 + NaOH
• Iron (ii) sulphate + sodium hydroxide > green precipitate
• FeSO4 + NaOH
• Iron (iii) sulphate + sodium hydroxide > brown precipitate
• Fe2(SO4)3 + NaOH