tests for cations II

• when cations are mixed with sodium hydroxide, they form a coloured precipitate. If they aren't a transition metal, they will form a white precipitate.
• Calcium - white
• Iron II - green
• Iron III - brown
• magnesium - white
• aluminium - white at first then turns colourless when in excess
• copper III - blue
• method - add sodium hydroxide drop wise to each test tube and observe
• carbonates react with dilute acids to form CO2 gas.
• Halide ions react in solution to form precipitates with silver nitrate solution in the presence of dilute nitric acid
• when atoms/ions are heated they gain energy and move to a higher energy level. When they calm back down, the energy is radiated as electromagnetic waves (electricity). Each element produces a unique wavelength. This is the idea behind flame tests and flame emission spectroscopy.