Year 9 CHEMISTRY REVISION WORKSHEET

Year 9 CHEMISTRY REVISION WORKSHEET

1. Substances can be pure or they can be mixtures.

(a) Which of these is a mixture?

(1)

(b) An impure substance

(1)

A. lowers boiling point B. increases boiling point C. no change in melting point D. increases melting point

(c)Water would be helpful in separating a mixture of

(1)

A.

sand and salt.

B.

iron and sulfur.

C.

iron and sand.

D

sand and sulfur.

(d) Figure shows some mixtures to be separated and possible methods of separation. Place a tick in one box in each row of the table to show the best method to separate the first named

substance from each of the mixtures.

(3)

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(e) Use the drawing below to answer the next question. The salt and water was separated from the insoluble impurities (dirt) using the apparatus shown on the right.

The salt and water was collected at X. Explain why the insoluble impurities were held at Y . (1) ............................................................................................................................. ............................................................................................................................. (f) P, Q, R and S are mixtures of food colourings. They are investigated using paper chromatography. Figure shows the chromatogram at the end of the experiment.

(i) Which piece of apparatus is needed to make measurements in a paper chromatography experiment? (1)

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(ii)Which mixture contains an insoluble food colouring?

(1)

(iii)Give a change that could be made to the experiment to obtain Rf value for the insoluble colouring.(1) ............................................................................................................................. .............................................................................................................................

(iv) Explain, by referring to Figure , which mixture is separated into the greatest number of soluble food

colourings by this chromatography experiment.

(2)

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............................................................................................................................. (g) Paper chromatography was used to find the composition of brown ink in a pen. The same liquid, paper and pen were used in each of the three experiments shown. They were started at different times, C first then B and finally A.

(i) Why is the ink dot above the level of the liquid in each beaker?

(1)

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(ii)What caused the dots of ink on the papers B and C to spread upwards?

(1)

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(iii)Why were colours, other than brown, seen in B and C as the ink moved up the paper?

(1)

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(h)Charles carried out a chromatography experiment to test which food colouring was present in a coloured drink. He used samples of three food colourings, X, Y and Z. He also tested a sample of the colouring in the drink. Charles obtained this chromatogram.

(i) Food colouring Y is banned. Explain how Charles can tell that the drink that he tested did not contain the banned food colouring. (1)

.............................................................................................................................

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(ii) Calculate the Rf value for the coloured substance in food colouring X.

(2)

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(i)Examine the diagram. (i) Complete the table correctly matching the labels A ? D in the diagram with the words in the table. (2)

Thermometer

Round bottomed flask

Tripod stand Bunsen Condenser Beaker

(ii)Name the separation process shown in the diagram.

(1)

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(iii)Identify the part of item C which is connected to the cold tap. Label in the diagram

(1)

(iv)How could you show that the water collected contains no salt?

(1)

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