preperation of salts

Question 1

titration is for

Answer 1

group 1, ammonium salts

Question 2

precipitation is for

Answer 2

insoluble salts

Question 3

adding insoluble reactant in excess is for

Answer 3

soluble salts

Question 4

titration method

Answer 4

1. Fill up a burette with 0.1 mol/dm of dilute nitric acid.
2. Pipette 25.0 cm’ of 0.1 mol/dm of aqueous sodium hydroxide into a conical flask.
3. Add a few drops of phenolphthalein indicator (or any other suitable indicator) to the solution in the conical flask.
4. Titrate the sodium hydroxide solution with the dilute nitric acid until the solution changes from pink to colourless permanently in a single drop (or the corresponding colour change based on the indicator used).
5. Note the volume of dilute nitric acid added.
6. Repeat the experiment without the indicator.
7. Add the same volume of acid (from step 5) from the burette. This gives a solution of the salt, without excess acid or alkali.
8. Heat the solution till saturated.
9. Allow the solution to cool for the crystals to form.
10. Filter the mixture to remove excess solution/water.
11. Wash the crystals with a small amount of cold distilled water.
12. Dry the crystals by pressing between sheets of filter paper.

Question 5

precipitation procedure

Answer 5

1. mix x solution and y solution in beaker
2. filter the mixture and collect Z as residue
3. wash the salt with cold de ionised water and wipe dry between 2 sheets of filter paper

Question 6

add insoluble reactant in excess procedure 1

Answer 6

1. add insoluble carbonate/ base/ meals into acid until no more carbonate/ base/ metals dissolve and is in excess
2. filter the mixture and obtain Z solution as filtrate
3. heat the filtrate gently until it is saturated
4. allow the saturated solution to cool for crystals to form
5. filter the mixture to collect the crystals
6. wash the soluble salt crystals with a small amount of cold distilled water and dry crystals between 2 pieces of filter paper

Question 7

why do you need to wash with cold deionised water

Answer 7

remove contaminant chemicals that are on the surface of the crystals

Question 8

titration uses

Answer 8

1 acid 1 alkali both soluble

Question 9

precipitation uses

Answer 9

2 aqueous solutions

Question 10

adding insoluble reactant in excess includes

Answer 10

adding an insoluble reactant into acid