test for ions

what are the different test for identifying positive ions

Flame tests and test for ammonium ions

flame tests

Dip a nichrome wire loop in concentrated hydrochloric acid to clean it and then dip it into the unknown compound. hold the loop in the blue flame and observe the colour change.

colour changes for flame test

Calcium = brick red. Strontium = red. Barium = Pale green

test for ammonium ions

add dilute sodium hydroxide solution into the unknown substance in a test tube and gently heat the mixture and then dip the red litmus paper into the mixture.

results for ammonia test

if ammonia is present the paper will turn blue

what are the different tests for identifying negative ions

test for sulfate ions, hydroxide ions, halide ions and carbonate ions.

test for sulfate ions

add dilute hydrochloric acid and barium chloride solution to a solution containing sulfate ions.

results for sulfate ions

white precipitate is formed if sulfate ions were present

test for hydroxide ions

dip red litmus paper into a solution that may contain hydroxides

result for test for hydroxide ions

the paper will turn blue.

test for halide ions

add dilute nitric acid and silver nitrate solution in a solution containing halide ions.

results for halide ions

chloride = white precipitate. bromide = cream precipitate. iodide = yellow precipitate.

how to tell the results for halide ions apart

add ammonia solution

results for ammonia solution and halide ions

silver chloride dissolves in dilute ammonia solution. silver bromide dissolves in concentrated ammonia solution. silver iodide wont dissolve in either.

test for carbonate ions

add hydrochloric acid to a solution that contains carbonate ions.

results for test for carbonate ions

the solution will fizz if the solution contains carbonate ions because the carbonate ions react with the hydrogen ions to give CO2

test for carbonate ions using limewater

bubble the gas through a test tube

results for test for carbonate ions using limewater

the limewater will go cloudy if the solution contains carbonate ions as carbon dioxide turns limewater cloudy.