Name: ___________________________________ Date: ______________________
Lesson 10: Separation of Mixtures
Section A: Multiple-choice Questions
Choose the correct answer and write its letter in the brackets provided.
1. Which of the following cannot be separated using a magnet?
A A mixture of iron and nickel powder.
B A mixture of steel and aluminium powder.
C A mixture of sulphur and cobalt powder.
D A mixture of iron and table salt.
2. Which of the following statements best explains why distillation is a physical method?
A Distillation can only be used to separate liquids which have different boiling points.
B Distillation cannot break down a compound in order to obtain its constituent elements.
C Distillation cannot separate a mixture in order to obtain its constituent substances.
D Distillation can only be used to retrieve the solvent from the
mixture.
3. The table below shows the information of three substances E, F and G.
A sample of mixture contains these three substances. After adding to a beaker containing water and alcohol, this mixture is filtered. Which of the following substances would be obtained when the filtrate is evaporated completely?
A Substance E only B Substance F and G
C Substance G only D Substance E and F
Substance Soluble in water Soluble in alcohol
E No Yes
F Yes Yes
G No No
4. Paper chromatography is a physical method to separate substances in a sample. Which of the following statement best explains why this method is used to separate the sample?
A It is used to separate a sample that is a solid at room temperature.
B It is used to separate a sample that has a limited sample size.
C It is used to separate components in a mixture based on their solubility in a solvent.
D It is used to separate components in mixture that can dissolve in water.
5. The steps shown in the table below, not in the correct sequence, are used to separate a mixture containing iron filings, table salt and sugar.
Which of the following shows the correct sequence to obtain these substances separately?
A 1 2 3
B 4 13 2
C 3 42 1
D 2 34
6. Which of the following mixture does not leave any residue after filtration?
A sea water
B wine
C tea
D fruit juice
Step Description
1 Heating to dryness 2 Using a bar magnet 3 Dissolving in alcohol 4 Filtering
7. Which of the following methods will separate a mixture of salt and iodine crystals?
A Dissolving the crystals and then distilling at different temperatures
B Dissolving the iodine crystals in alcohol, filtering out the salt, then evaporating the iodine.
C Heating the crystals and then collecting the iodine crystals on a filter funnel placed upside down over the container.
D Dissolving the crystals, then crystallizing the iodine and evaporating the salt.
8. In which one of the following is the set up for paper chromatography is correct?
9. Which one of the following is not a mixture?
A pure water B blood
C orange juice D concrete
( C )
( A ) ( D )
A B
10. Which of the following indicates the main difference between liquids W and Z?
W Z
A heated mixture cooled mixture
B mixture at boiling point purified, cooled solution
C mixture pure solute
D mixture pure solvent
Section B: Structured Questions
Write your answers in the spaces provided.
1. With the help of a specific example, explain how a mixture is different from a compound.
Mixture: Does not contain fixed proportion of its components; shows properties of its components;
no chemical changes take place, hence can be separated into individual components by physical methods.
E.g. air can be separated into different fractions.
Compound: components are combined chemically in a fixed Ration; a new substance its formed with its own properties; needs to split the substance into its elements by chemical methods.
E.g. carbon dioxide ( two oxygen atoms and one carbon atom in one molecule) has properties entirely different from its constituent elements : oxygen (supports combustion) and carbon (a black solid); carbon dioxide is a gas which extinguishes fire.
2. (a) What is an alloy? Give an example of an alloy.
A mixture of metals. Steel.
(b) Name the elements present in steel and state one use of steel.
Carbon and iron. To build ships and bridges.
3. (a) Write word equations for each of the following processes:
(i) Respiration
glucose + oxygen carbon dioxide + water
(ii) Photosynthesis
(b) Which of the substances in the equations in a(i) and a(ii) are compounds? Explain your answer.
a(i) glucose (contains C,O and H), carbon dioxide (C and O) and water (H, O).
4. (a) Label the diagram below.
(b) What is the purpose of adding B into the flask?
To maintain even/smooth boiling.
(c) What is the purpose of the part labeled A?
To cool and condense the water vapour so that pure liquid distillate can be collected.
5. A student used a pen to draw the starting line across a piece of
chromatography paper. He then placed a sample of dye on the drawn line for analysis. Is the student doing the right thing? Why?
No. The components present in the ink of the pen will be separated upon being dissolved by the solvent. The
Water out
Condenser
Homework Question
The structure of a borazine molecule is shown below.
(a) Write the symbols of elements present in this molecule.
B, N and H
(b) What is its molecular formula?
B3N3H6
(c) The liquid form of this substance reacts with water to form the gases ammonia and hydrogen and an aqueous solution of boric acid. Write a balanced chemical equation for this reaction.
