Testing For Halliee Ions Flashcards
Why is it impossible to distinguish between hallide ions in a solution ?
Because hallide ion solutions are all colourless
State the reagents for testing for hallide ions using acidified silver nitrate solution .
AgNO3 (aq) with HNO3 (aq)
State the test for hallide ions using acidified silver nitrate solution
When you add the acidified silver nitrate and HNO3 which both contain the NO3 - ion
To suspected solution that contain hallide ions
It produces a silver hallide product
What is the property of nearly all silver halllides ?
They are nearly all insoluble in water with the exception of silver fluoride
So you get no visible change with NaF
What is formed with all the other silver hallide that are insoluble in water ?
A coloured precipitate will form
What coloured precipitate does AgCl (s) form ?
A white precipitate
What coloured precipitate does the AgBr (s) form ?
Cream precipitate
What coloured precipitate does the AgI (s) form ?
A yellow precipitate
State the ionic equation for the formation of the precipitates with AgNO3
Notes
Why do you add the nitric acid ?
Because it reacts with the impurities in the substances that can react with the silver and produce a misleading white precipitate which will,lead to a misleading result that makes us think that chloride ions were present
What is the most common impurity ?
The carbonate ion CO3 2-
Which reacts to make Ag2CO3 (s) which is a white precipitate
State the ionic equation for the reaction of nitric acid and carbonate ions ?
Notes
How do you distinguish between the similarity of the coloured precipitates of cream and white ?
Use a follow up test using a dilute ammonia solution NH3 (aq)
State the test for distinguishing between precipitates ?
Add dilute ammonia solution to the precipitates
And swirl it around.
How will you know if the precipitate was white ?
The precipitate would have dissolved and solution would go back to being colourless
