Test for Ions
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Describe flame tests used to identify group 2 ions
Dip a nichrome wire loop in concentrated hydrochloric acid. Then dip the wire loop into the unknown compound. Hold the loop in clear blue part of the Bunsen flame. Observe colour change in the flame
Colour of Calcium Ion in Flame Test
Brick-red
Colour of Strontium Ion in Flame Test
Red
Colour of Barium Ion in Flame Test
Pale green
Describe using red litmus paper to test for ammonium ions
Ammonia gas is alkaline so can test for it using damp piece of red litmus paper. Needs to be damp so ammonia gas can dissolve. If ammonia’s present, the paper will turn blue (ie from red to blue)
Describe using NaOH to test ammonia for ammonium ions
Add some dilute sodium hydroxide solution to a substance in a test tube and gently heat the mixture. If ammonia’s given off, ammonium ions must be present
Test for Sulfates with HCl and Barium Chloride
To identify a sulfate ion, add a little dilute hydrochloric acid, followed by barium chloride solution. If a white precipitate of barium sulfate forms, it means the original compound contained a sulfate
Using a pH indicator to test for hydroxides
Dip a piece of red litmus paper into the solution. If hydroxide ions are present, the paper will turn blue
Test for halides with silver nitrate solution Results for: Chloride Bromide Iodide
Add dilute nitric acid followed by silver nitrate solution. White precipitate of silver chloride. Cream precipitate of silver bromide. Yellow precipitate of silver iodide
Using hydrochloric acid to test for carbonates
By adding dilute hydrochloric acid, a solution containing carbonate ions will fizz. (carbon ions react with the hydrogen ions in the acid to give carbon dioxide). Test for CO2 using limewater. CO2 turns limewater cloudy- just bubble the gas through a test tube of limewater. If the limewater goes cloudy, your solution contains carbonate ions