2nd Form – Separating substances test

Name:

Read the questions carefully. THINK. Then answer them.When you have finished, PLEASE CHECK YOUR ANSWERS CAREFULLY.

1. Which of these methods would separate sand and water?

A freezing B crystallising

C filtering D dissolving

2. Fractional distillation can be used to separate some alcohol from water. This method of separation uses the fact that alcohol and water:

A contain different sized molecules B contain different pigments

C boil at different temperatures D burn at different temperatures

3. To make instant coffee powder, crushed coffee beans are boiled in water. The solution is strained to remove solids. After this it is boiled dry to leave the coffee powder.The scientific name for straining a solution is:

A filtering B dissolving

C evaporating D mixing

4. Which of these mixtures could be separated by distillation?

A sand and salt B salt and chalk

C salt and water D sugar and copper sulphate

5. An ink was found to contain both red and blue dyes. In a chromatography experiment the red moved 6 cm in the same time that the blue moved 2 cm. How far would the blue move when the red pigment had moved 18 cm?

A 3 cm B 6 cm

C 9 cm D 18 cm

6. Some salt has been mixed with sand. What is the correct order for carrying out the stages required to purify the salt using water as a solvent for the salt?

A distilling, filtering, evaporating

B dissolving, filtering, crystallising

C evaporating, filtering, crystallising

D filtering, dissolving, crystallising

7. The following are processes used in chemistry to separate mixtures

A chromatography

B crystallisation

C distillation

D evaporation to dryness

E filtration

Choose from the above list the most suitable process for

i) Obtaining copper sulphate crystals from aqueous copper sulphate Answer =

ii) Obtaining pure water from aqueous sodium chloride Answer =

iii) Finding out how many dyes are present in black ink Answer =

iv) Obtaining insoluble limestone from a mixture of limestone and water Answer =

8. Each of the following sets of apparatus is identified by a letter

A flask and Liebig condenser

B separating funnel and beaker

C beaker, filter funnel and evaporating dish

D pipette, beaker and stirring rod

i) Which set of apparatus (A,B,C or D) would be most suitable for separating ethanol from a mixture of ethanol and water?

ii) Which set of apparatus (A,B,C or D) would be most suitable for obtaining copper sulphate crystals from a mixture of copper sulphate and insoluble copper oxide?

iii) Which set of apparatus (A,B,C or D) would be most suitable for obtaining water from a mixture of oil and water?

9. Chromatography can be used to

A colour aluminium

B compare the colour fastness of dyes

C produce a pattern with dyes on fabric

D separate dyes

10. Which of these methods of separation involves the change of a liquid to a gas and of the gas back to a liquid again?

A crystallisation B evaporation

C distillation D filtration

11. Which of these methods would be used to separate coloured substances in a sample of coloured soft drink (gaseosa)?

A distillation B chromatography

C crystallisation D filtration

12. Liquids in which substances dissolve are called:

A bleaches B solutes

C solvents D solutions

13. Describe in detail how you would make a chromatogram to compare the inks from 3 different pens (4 marks)

14. Draw a scientific diagram showing the apparatus you would use to filter a mixture of sand and water (3 marks)