Identifying Halogens in Solution

How can you test for halides?

Use the silver nitrate test

What happens if you're testing solid substances for halide ions?

Dissolve each of them separately in distilled water to make solutions

What should you do once you've got solutions of substances that you're testing?

Use a pipette to add about 3cm3 of each solution to separate test tubes

What can you do so you don't get confused about which is which?

Label each test tube

How can you record results?

Make a table, include each sample that you're testing and leave space to record whether a precipitate is formed with silver nitrate

What should you add, using a pipette?

Few drops of dilute nitric acid to each test tube

Why should you add a few drops of nitric acid?

It gets rid of any unwanted ions that might mess up the test results.

What should you add, using a pipette, after using nitric acid?

A few drops of aqueous silver nitrate to each test tube

When will a precipitate of the silver halide be formed?

If there are chloride, iodide, or bromide ions present

What identifies the halide?

Colour of the precipitate

What do chloride ions give?

White precipitate

What do bromide ions give?

Cream precipitate

What do iodide ions give?

Yellow precipitate.

What makes it easier to tell the halides apart?

Use dilute or concentrated ammonia

What should you add, using a pipette, to each silver halide precipitate suspensions?

Dilute ammonia

What's important to do when adding ammonia?

Same amount of ammonia as the amount of silver halide precipitate suspension you have

What should you do once adding dilute ammonia and concentrated ammonia ?

Stir mixtures using a glass rod and record whether any precipitates dissolve in ammonia.

What happens if any precipitates haven't dissolved?

Add concentrated ammonia to solution, roughly the same volume as the dilute ammonia.

What's the result for chloride?

Precipitate dissolves in dilute ammonia

What's the result for bromide?

Precipitate doesn't dissolved in dilute ammonia but will in concentrated ammonia.

What's the result for iodide?

Precipitate is insoluble in dilute and concentrated ammonia.