Required practicals C5

Question 1

How to prepare an insoluble salt by precipitation

Answer 1

1. Mix two soluble salts together, so they react
2. Filter the mixture to separate the products produced (soluble and insoluble salt produced)
3. Wash the insoluble salt on the filter paper
4. Dry the insoluble salt in warm oven

Question 2

How to make a copper salt

Answer 2

1. Using a measuring cylinder, measure 20cm cubed of acid into the beaker
2. Stand the beaker on a tripod and gauze and warm gently
3. Add half a spatula of copper oxide powder into the acid and stir using the glass rod
4. Keeping the acid warm continue adding the copper oxide until no more dissolves
5. Allow to cool and then filter the mixture and discard the residue on the filter paper.
6. Pour the filtrate into an evaporating basin. Heat the solution until volume is halved
7. Remove from heat and leave to crystalise

Question 3

How to make a salt from a metal carbonate

Answer 3

1. Using a measuring cylinder, measure 20cm3 of acid into the beaker.
2. Add half a spatula of one of the metal carbonates into the acid and stir with the glass rod
3. Continue adding the metal carbonate in small amounts until no more dissolves and there is no more fizzing
4. Set up a filter funnel and filter paper in a conical flask as shown below. Filter the mixture and discard the unreacted metal carbonate
5. Pour the filtrate into an evaporating basin and place it on a beaker of water. Heat the water gently until the volume of the solution in the evaporating dish is halved.
6. Remove from the heat. When it is cool, stand the evaporating basin on a piece of paper. Leaving overnight to crystallise
7. Next day, remove crystals from concentrated solution with a spatula and gently pat them dry between two filter paper.

Question 4

Why is the acid heated

Answer 4

Make reaction quicker

Question 5

After reaction is complete, some sodium magnesium oxide remains. explain why.

Answer 5

Left in excess

Question 6

The student removed the solid magnesium oxide from the solution. Suggest what the student should do to the solution to form magnesium chloride crystals

Answer 6

Heat it to evaporate it

Question 7

Mass of magnesium chloride crystals was less than the student expected

Answer 7

Some magnesium chloride did not crystalise out