Preparation of Salts

Question 1

state the method to prepare a soluble SPA salt

Answer 1

Titration

Question 2

state the method to prepare a soluble non SPA salt

Answer 2

Acid + Excess Solid

Question 3

state the method to prepare a insoluble salt

Answer 3

Precipitation

Question 4

Precipitation general formula

Answer 4

soluble salt + soluble salt -> insoluble salt + soluble salt

Question 5

Titration general formula

Answer 5

acid + alkali - salt + water

Question 6

Describe the method to prepare sodium nitrate

Answer 6

Sodium nitrate - Soluble SPA salt, Titration

1. Pipette 25.0cm3 of sodium hydroxide into a conical flask and add in a few drops of indicator (methyl orange), stir.
2. Fill the burette with dilute nitric acid and slowly add it into the flask until it changes colour (yellow to orange) Note the volume of acid used.
3. Repeat step 1 but without the indicator, and add in the predetermined volume of acid from step 2, stir
4. To get pure salt crystals, heat the mixture from step 3 until saturated
5. Allow it to cool and crystallize
6. Wash the crystals with cold distilled water and press dry with filter paper.

Question 7

Describe the method to prepare ammonium sulfate

Answer 7

Ammonium sulfate - Soluble SPA salt, Titration

1. Pipette 25.0cm3 of ammonium hydroxide into a conical flask and add in a few drops of indicator (methyl orange), stir.
2. Fill the burette with dilute sulfuric acid and slowly add it into the flask until it changes colour (yellow to orange) Note the volume of acid used.
3. Repeat step 1 but without the indicator, and add in the predetermined volume of acid from step 2, stir
4. To get pure salt crystals, heat the mixture from step 3 until saturated
5. Allow it to cool and crystallize
6. Wash the crystals with cold distilled water and press dry with filter paper.

Question 8

Describe the method to prepare barium sulfate

Answer 8

barium sulfate - SuBaCaPb insoluble, Precipitation

1. Add aqueous barium nitrate and aqueous Sodium sulfate together and stir.
2. Filter the mixture and collect the residue of barium sulfate
3. Wash the residue with cold distilled water and press dry between filter paper.

Question 9

Describe the method to prepare lead(II)chloride

Answer 9

lead(II)chloride - insoluble, Precipitation

1. add together lead (II) nitrate and sodium chloride together and stir.
2. filter the mixture and collect the residue
3. wash the residue with cold distilled water and press dry between filter paper.

Question 10

Describe the method to use to prepare magnesium sulfate

Answer 10

Magnesium Sulfate: a soluble non SPA salt : excess solid and acid reaction
1. acid + reactive metal > salt + hydrogen
2. acid + base > salt + water
3. acid + carbonate > salt + water + carbonate
Steps:
1. add excess magnesium powder/ magnesium oxide powder/ magnesium carbonate powder into dilute sulfuric acid while stirring
2. filter the mixture and collect the filtrate, which is magnesium sulfate
3. heat the filtrate up until saturated
4. allow the saturated solution to cool and crystallize
5. wash the crystals with cold distilled water and press dry between filter paper

Question 11

Describe the method to prepare copper(II) chloride

Answer 11

Copper(II) Chloride : a soluble non SPA salt : excess solid and acid reaction
1. acid + reactive metal > salt + hydrogen
2. acid + base > salt + water
3. acid + carbonate > salt + water + carbonate
** Do note that copper(II) metal is unreactive and does not react with acid therefore we should not write copper(II) metal.
Steps:
1. add excess copper(II) oxide powder/ copper(II) carbonate powder into dilute hydrochloric acid while stirring
2. filter the mixture and collect the filtrate, which is copper(II) chloride
3. heat the filtrate up until saturated
4. allow the saturated solution to cool and crystallize
5. wash the crystals with cold distilled water and press dry between filter paper