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KCSE CLUSTER TESTS 19

Chemistry Paper 2

1.

a) The table below gives information on four elements by letter K,L,M and N.Study it answer the questions that follow. The letters do not represent the actual symbols of the elements.

i) Which two elements have two similar chemical properties?

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ii) What is most likely formula of oxide of L?

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iii) Which one of elements is the strongest reducing agent? Explain ..................................................................................................................

iv) Explain why ionic radius of N is less than that of M.

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v) Explain why the ionic radius of L is bigger than its atomic radius.

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b) Study the information given in the table below and answer the questions that
follow. The letters do not represent the actual symbols of the elements.

(i) Which element (i)Is in gaseous state at room temperature?Explain

(Take room temperature to be 298K)
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(ii)Does not form an oxide? Explain

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(ii) Write the (i)Formula of the nitrate of element T.

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(ii) Equation for the reaction between elements U and S.

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13 marks

2.

a) What is meant by molar heat of solution?

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b) The lattice energy of sodium bromide and hydration energies of sodium and bromide ions are: 733,406 and 335kJ/mole respectively. (i) Complete the energy level diagram below by inserting the values of

ii) Determine the molar heat of solution of solid sodium bromide.
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c) 24g of potassium nitrate solid was added to 120cm3 of water in a plastic beaker. The mixture was stirred gently and the following results were obtained.

Initial temperature =

Final temperature

i) Calculate the enthalpy change for the reaction.

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ii) Calculate the molar enthalpy change for the dissolution of potassium nitrate. (K=39, N=14, O=16)

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d) Use the information below to answer the questions that follows

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11 marks

3.

Give the names of the following compounds.

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b) Study the flow chart below and answer the questions that follow.

i) Name compounds

A...........................................................

B...........................................................

ii) State the conditions and reagents necessary for the following steps to take place.

Step I .............................................................................................................

Step II ............................................................................................................

iii) Give the name of the process in:

Step II .............................................................................................................

Step V .............................................................................................................

iv) Write an equation for the complete combustion of methane.

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c) The scheme below was used to prepare a cleaning agent. Study it and answer the questions that follow.

i) What name is given to the type of cleaning agent prepared by the method shown in the scheme?

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ii) Name one chemical substance added in step II.

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iii) What is the purpose of adding the chemical substance named in c(ii) above.

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iv) Explain how an aqueous solution of the cleansing removes oil from utensils during washing.

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12 marks

4.

a) The diagram below shows an incomplete set-up used to prepare and collect ammonia gas.

i) Name solid M

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ii) Complete the diagram to show how a dry sample of ammonia gas can be collected.

iii) Name one use of ammonia

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b) Study the flow chart below and answer the questions that follow

i) What conclusion can be drawn form step I only. Explain ......................................................................................................

ii) Write the formula of anion present in residue U. Give a reason for your answer.

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iii) Suggest the identity of the Cation present in solution Z.

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iv) Name the two salts present in mixture Q

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10 marks

5.

a) The diagram below represents the electrolysis of dilute sulphuric (VI) acid.

i) Name gases A and B.

A..................................................................................................

B................................................................................................

ii) Write ionic equation for the formation of gas A.

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iii) At what electrode does reduction takes place? Explain your answer.

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iv) Name the most suitable electrodes for this experiment. Explain your answer.

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b) The table below gives standard electrode potentials for the metals represented by the letters D,E,F and G.Study it and answer the questions that follow.

i) Which metal can be displaced from a solution of its salts by all the other metals in the table. Give a reason.

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ii) Metals F and G were connected to form a cell as shown in the diagram below.

I. Write the equation for the reaction that occurs at electrode G .............................................................................................

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II. On the diagram, indicate with an arrow the direction in which electrons would flow.

III. What are the two function of the salt bridge.

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iii) A current of 0.5A were passed through the fused chloride of W for 32 minutes and 10 seconds. 0.44g of W were deposited at the cathode. Given that element W has a relative atomic mass of 88. Determine the charge on the ion of W. (IF=96500C) .............................................................................................

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10 marks

6.

a) What is meant by a saturated solution?

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b) The table below shows solubilities of a salt P in water at different temperatures.

i) Plot a graph of solubility of salt P against temperature

ii) Use your graph to determine the solubility of salt P at 250c.

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iii) Calculate the mass of salt P that would dissolve in 45g of water at 250c. ..................................................................................................................

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c) The table below gives the solubilities of potassium bromide and potassium sulphate at and

When an aqueous mixture containing 60g of potassium bromide and 7g of potassium sulphate in 100g of water at was cooled to some crystals were formed.

i) Identify the crystals

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ii) Determine the mass of the crystals formed.

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iii) Name the method used to obtain the crystals.

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iv) Give the application of the method named in (iii) above.

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11 marks

7.

a) i) What are allotropes.

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ii) Name two allotropes of sulphur.

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b) Study the flow chart below and answer the questions that follow.

i) Write equation for the reaction taking place at

I. Roasting furnace

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II. Absorption tower

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ii) The reaction taking place in chamber K is

I. Explain why it is necessary to use excess air in chamber K.

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II. Name another substance used in chamber K

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III. Name a chemical substance that can be used to dry sulphur (IV) oxide.

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c) State and explain what you would observe if concentrated sulphuric (VI) acid is added to

i) Cane sugar

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ii) Copper (II) sulphate crystals

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d) State two uses of sulphuric (VI) acid.

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11 marks

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