Separation Techniques - exam practice
Separation Techniques
Question 1 of 10
The diagrams below show three different mixtures.
Define the term 'mixture'.
Which of the diagrams above depicts a mixture of elements?
Which of the diagrams above depicts a mixture of compounds?
Which two of the following substances are mixtures?
Substances in a mixture can be separated using different methods.
Draw one line from each substance and mixture to the most appropriate method of separation.
Sand does not dissolve in water.
A student wants to separate a mixture of sand and water.
Which method can the student use to separate the mixture of sand and water?
Draw and label a diagram of the apparatus that the student could use.
In your drawing, indicate:
- where the water would be collected
- where the sand would be collected
Explain why the same method cannot be used to separate a mixture of ethanol and water.
Water was separated from salt water by simple distillation in a school laboratory.
Use the words 'boils', 'cools', 'condenses' and 'water vapour' to explain how salt water can be distilled into pure water.
Suggest why it is not safe to drink the distilled water sample prepared in the school laboratory.
Describe how to obtain salt crystals from salt water by crystallisation.
Hexane and water are immiscible.
Describe how separate samples of hexane and water can be obtained from a mixture of hexane and water.
A mixture of three liquids was fractionally distilled.
The image below shows the apparatus used.
Explain the difference between a mixture and a compound.
The table below shows the boiling points of the three liquids in the mixture.
Which liquid in the table would be the first to distil and be collected in the beaker?
Suggest what would happen to the temperature of the water as it flows through the condenser.
Describe how oxygen and nitrogen are obtained from liquid air by fractional distillation.
A student uses the apparatus below to separate water from a salt solution.
What is the name of the process used by the student?
What temperature would you expect the thermometer to show?
Describe how the process shown in the image produces pure water from salt solution.
Water obtained by distillation does not need to be sterilised and is safe to drink.
Suggest why.
Substances are separated from a mixture using different methods.
Draw one line from each method of separation to the substance and mixture it would separate.
To make crude oil more useful, it is separated into different fractions with different uses.
What is the name of the process used to separate crude oil into different fractions?
Describe and explain how petrol is separated from the mixture of hydrocarbons in crude oil.
Paper chromatography is one method of testing the dyes present in cake icing.
Explain what happens during the process of chromatography.
Plan an investigation, using paper chromatography, to determine the Rf value for a blue food dye in a sample of cake icing.
Your plan should include the following apparatus:
- a solvent
- a beaker
- chromatography paper
The Rf value of the blue dye is 0.60.
The distance moved by the blue dye is 5.7 cm.
Calculate the distance moved by the solvent.
Food colourings are used to coat some chocolate sweets.
Some of these food colourings are suspected of causing asthma and rashes in children.
A scientist used chromatography to investigate whether the problem food colourings were used in two sweets, S and P.
The results are shown in the image below.
How many food colourings are there in sweet P?
In chromatography, the Rf value can be calculated using the following equation:
Which food colouring has a Rf value of 0.3?
From the chromatogram, what conclusions can the scientist make about the colourings in sweets S and P?
A student has a mixture of three substances.
The table below shows information about these substances.
Describe how the student can separate the mixture to get pure samples of all three substances.
Explain why each method of separation works.
Nitric acid (HNO3) can be used to neutralise sodium hydroxide (NaOH).
Sodium nitrate (NaNO3) and water are made.
Write a balanced symbol equation for this reaction.
Describe how dry sodium nitrate crystals can be obtained from the sodium nitrate solution produced in this reaction.