Chemical tests

Question 1

Name the steps of testing for halide ions in aqueous solution

Answer 1

1.dissolve sample if not already in solution
2.add dilute HNO3 / nitric acid to remove carbonate ions as these would also produce a precipitate
3.add AgNO3(aq) /silver nitrate solution and observe
4.add dilute NH3 solution /ammonia and observe
5.if needed add concentrated NH3 solution /ammonia

Question 2

What are the different precipitates formed by the halides with silver nitrate solution?

Answer 2

F- colourless- AgF is soluble in water
Cl- white precipitate
Br- cream precipitate
I- yellow precipitate

Question 3

What happens to Cl/Br/I in dilute ammonia?

Answer 3

Cl- ppt dissolves completely
Br- ppt is sparingly soluble
I- ppt is insoluble

Question 4

What happens to Cl/Br/I in concentrated ammonia?

Answer 4

Cl/Br- dissolves completely
I- doesn’t dissolve

Question 5

What is:
-the melting/boiling point
-the typical state under standard conditions
-conducts electricity?
-soluble in water?

For ionic bonding?

Answer 5

-high mp/bp
-solid
-not as a solid as ions are held in place but yes when liquid/molten
-soluble in water

Question 6

What is:
-the melting/boiling point
-the typical state under standard conditions
-conducts electricity?
-soluble in water?

For a simple covalent molecule?

Answer 6

-low mp/bp
-May be solid like I2 but generally liquid/gas
-doesnt conduct electricity
-solubility in water depends on on how polar the molecules are

Question 7

What is:
-the melting/boiling point
-the typical state under standard conditions
-conducts electricity?
-soluble in water?

For giant covalent/macromolecular?

Answer 7

-high mp/bp
-solid
-no (except graphite)
-insoluble in water

Question 8

What is:
-the melting/boiling point
-the typical state under standard conditions
-conducts electricity?
-soluble in water?

For metallic bonding?

Answer 8

-high mp/bp
-solid
-yes can conduct
-insoluble in water

Question 9

How to test for OH- ions?

Answer 9

universal indicator