Testing for group 7 ions

Question 1

Step 1

Answer 1

Add dilute nitric acid to a sample congaing group 7 compounds

Question 2

Why is dilute nitric acid to the mixture?

Answer 2

To remove unwanted carbonate ions which would form a white precipitate with the silver ions = false positive

Question 3

Step 2

Answer 3

Silver nitrate solution drops added to the tube

Question 4

Silver nitrate solution

Answer 4

AgNO₃

Question 5

What is formed after silver nitrate solution is added?

Answer 5

Silver halide eg AgCl
AgBr
AgI

Question 6

How to identify which halide ions present in solution?

Answer 6

The colour of the precipitate

Question 7

AgF colour

Answer 7

No precipitate formed

Question 8

AgCl

Answer 8

White precipitate formed

Question 9

AgBr

Answer 9

Cream precipitate formed

Question 10

AgI

Answer 10

Yellow precipitate formed

Question 11

How to differentiate silver halide precipitates?

Answer 11

Add ammonia solution
Measure how soluble this solution formed is

Question 12

AgCl solubility in ammonia solution

Answer 12

Precipitate dissolves to form a colourless solution

Question 13

AgBr solubility in ammonia solution

Answer 13

Will only dissolve after a while if the solution is concentrated
Will remain unchanged if dilute

Question 14

AgI solubility in ammonia solution

Answer 14

Does not dissolve