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Classified Chemistry E d e x c e l
6
4CHO/1C_Topic_2
Topic 2
2 – M ethods of of separati on
Mostafa Barakat (0100 165 44 62)
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4CHO/1C_Topic_2
1) Sample Assessment Materials 2011 Q (2) 2. The diagrams show some pieces of apparatus you can find in a chemistry laboratory.
(a) Name the pieces of apparatus, B and E. Use only names from the box. Funnel
Measuring cylinder
Pipette
Stop clock
Thermometer
stop clock B ........................................................................................................................ funnel E ......................................................................................................................... (2) (b) Two of the pieces shown can be used to measure the volume of a liquid. State the letters of these two pieces.
C D ........................................................ and ............................................................ (2)
2 – M ethods of separati on
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4CHO/1C_Topic_2
(c) One of the pieces shown cannot be used to make a measurement. State the letter of this piece.
E ............................................................................................................................ (1)
2) June 2011 Q (4) 4 Four separate food dyes (C, D, E and F) and a mixture of food dyes (X) were investigated using paper chromatography. The diagram shows the apparatus used.
(a) Why should the water level be below the food dyes?
to stop the dyes from dissolving into water ............................................................................................................................ (1) (b) During the experiment the water rises up the paper. The experiment is stopped just before the water reaches the top of the paper. The diagram shows the paper after it has been removed from the beaker and dried.
2 – M ethods of separati on
Mostafa Barakat (0100 165 44 62)
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4CHO/1C_Topic_2
(i) Which of the food dyes C, D, E and F does X contain?
C and D ............................................................................................................................ (1) (ii) Suggest why food dye F did not move up the paper during the experiment.
because it is insoluble in water ............................................................................................................................ (1) (c) Each food dye has an Rf value that can be calculated using this expression:
Record the distances for food dye D in the table below and calculate its Rf value.
Distance moved by food dye D from base line in mm
52-55
Distance moved by solvent from base line in mm
67-68
Rf value
0.76-0.82 (3)
2 – M ethods of separati on
Mostafa Barakat (0100 165 44 62)
Classified Chemistry E d e x c e l
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4CHO/1C_Topic_2
3) Jan 2012 Q (1) 1 Salt is soluble in water, but sand is insoluble in water. This difference allows a mixture of salt and sand to be separated using this apparatus.
(a) Use words from the box to complete the sentences. Each word may be used once, more than once or not at all. Beaker
Bunsen burner
Burette
Conical flask
Funnel
Glass rod
Thermometer
Water
beaker In Step 1, the mixture of salt and sand is placed in a ........................................ water glass rod containing ........................................ and stirred with a ..................................... funnel In Step 2, the mixture from Step 1 is poured through a .................................. conical flask into a ............................................... water In Step 3, the liquid is transferred to a basin to allow the.......................... to be removed. (6) (b) (i) What should be placed in A before the mixture from Step 1 is poured through it?
filter paper ............................................................................................................................ (1) (ii) What is the solid removed in Step 2?
sand ............................................................................................................................ (1) 2 – M ethods of separati on
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4CHO/1C_Topic_2
(c) Place crosses ( ) in two boxes to show the names of two processes used in this separation. Chromatography Condensation Distillation Evaporation Filtration Sublimation
4) June 2012 Q (1_a, b) 1 A student was asked to find the mass of salt dissolved in 100 cm3 of sea water. She was given the following instructions. Step A Weigh an empty evaporating basin Step B Transfer 50 cm3 of sea water into the basin Step C Heat the sea water in the basin until all the water has evaporated Step D Allow the basin and residue to cool Step E Weigh the basin and residue of salt (a) During the experiment, the student used several pieces of apparatus. Some of them are shown in the table. Complete the table. Image of apparatus
because salt solution may spit out when evaporating the salty water ............................................................................................................................ ............................................................................................................................ (2)
5) June 2013 Q (9_a) 9 The diagram shows some pieces of apparatus used to me asure volumes.
A student was given a large bottle containing sodium hydroxide solution and a supply of dilute sulfuric acid of known concentration. He was allowed to use normal laboratory apparatus, including the pieces of apparatus shown in the diagram. He was told to plan an experiment to find the concentration of the sodium hydroxide solution.
2 – M ethods of separati on
Mostafa Barakat (0100 165 44 62)
Classified Chemistry E d e x c e l
13
4CHO/1C_Topic_2
This is his plan. Step 1 Obtain about 150 cm 3 of each solution. Step 2 Use a measuring cylinder to add exactly 25.0 cm 3 of sodium hydroxide solution to a conical flask. Step 3 Add a few drops of universal indicator to the conical flask. Step 4 Use a burette to add the sulfuric acid to the conical flask until the indicator changes colour. (a) (i) Give the name of the most suitable piece of apparatus in the diagram that should be used in Step 1. (1)
beaker ............................................................................................................................ (ii) Give the name of the piece of apparatus in the diagram that should be used instead of a measuring cylinder in Step 2. (1)
Pipette ............................................................................................................................ (iii) State why universal indicator is not a good choice for this experiment and suggest an indicator that would be more suitable. (2) ............................................................................................................................
because colour change is gradual not which can not defined easily ............................................................................................................................ ............................................................................................................................ ............................................................................................................................ (iv) Why is a pipette not suitable for adding the acid in Step 4? (1) 3
because pipette measures only one volume 25 cm ............................................................................................................................ ............................................................................................................................
