cameroon gce O/L june 2000 chemistry Paper 2

cameroon  gce june 2000 chemistry Paper 2

 

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JUNE 2000

SECTION A

 

1. The table gives some information about six elements, U, V, W, X, Y and Z. These letters are NOT the usual symbols of the elements. Using only the letters U-Z answer the questions that follow.

Element	Atomic Number	Electronic Configuration
U		2,8/18,7
V	11	1
w		2,8,14,2
X		2,8,4
Y	18
z	17

• Give :

(i) The atomic number of U………

(ii) The electronic configuration of Z   (2marks)

(b) Which one of the elements in the table does not form compounds?

Give a reason for your answer………………………………….

• Which two of the elements in the table belong to the same group of periodic table? Give the name of the group.

Elements ………group. ……………………. (2marks)

1. d) (i) Write tire formula of the compound formed between X and Z ………..

(ii) Write the formula of the sulphate of W… (2marks)

• From the elements U-Z select the element which

Is a transition metal………………………………………….. (2marks)

• What type of compound is formed between V and

Hydrogen?……………………………………………… (1 mark)

 

 

 

 

2.

 Sodium hydroxide is manufactured industrially by electrolysis.

(a)  Name the electrolyte used………………….. (1 mark)

• State the material of which each electrode is made

Up. Cathode………….. …anode …………….  (2marks)

• Write an ionic equation for the reaction by which

Sodium hydroxide is produced…………………. (2marks)

• Name two by-products of the process and give one large scale use of each by-product

• How would sodium hydroxide pellets be obtained

From tire solution…………………….. ……………… (1 mark)

 

 

 

3. On heating 5g of granulated zinc with excess 2MHC1 (aq) V cm³ of hydrogen gas was produced in 5 minutes

• Why is the HCL (aq) used in excess? …………. (1 mark)

(b)The table below shows the other conditions under which the reactions take place. Complete the table by stating whether V increases, decreases or remind the same. In each case give the reason.

Experiment  condition	Results	Reasons
i.     5g of powder zinc and excess 2M HO (aq) heated for 5 minutes ii.     5g of granulated zinc an d excess 2MHQ (aq) heated for 5tnanuies iii.   5g of granulated zinc and excess 2M HG (aq) at room temperature

(c)(i) Write the equation for the reaction…………………

(ii) if the reaction continued until all the zinc is used up, calculate the volume of hydrogen produced measured at room temperature and atmospheric pressure                      (3marks)

 

 

 

 

 

4.

    B

Structure A and B above represent two crystalline forms of carbon

• Name the crystalline form represented by

• A   …………………………………….  (1 mark)

• B:……………………………………………………… (1 mark)

• What term is used to describe this phenomenon

Exhibited by carbon?……………………………….. (1 mark)

     (c) Complete the table below to bring out the differences in

           The physical properties given

Property	A	B	Reason for Difference.
Hardness
Electrical conduction

(d) How would you show by experiment that A and B are different forms of the same elements?

………………………………………………… (2marks)

(e)  Give one use of each of the two crystalline   forms. A…………B……… (2marks)

 

 

 

 

 

 

 

 

5. Given below are the molecular formula of some <

Hydrocarbons A: C4H10B:C2H4 C: C₂H₂ D: CH₄ E: C₆H₆

1. Name the hydrocarbons A,B,C and E

AM: .B        C…… E…………………………….. , (2marks)

1. From A-I| select the hydrocarbon that is

• Obtained by decarboxylation of sodium ethanoate (Sodium acetate)

• The main component of kitchen gas in Cameroon

• Used as a monomer in the production of an

Important plastic……………… L……….

• An aromatic hydrocarbon………………… “(2marks)

• State two conditions required for the formation

Of a hydrocarbon plastic …..  (2marks)

• What is the structural difference between A and

B?………………………………………………….. ………. (2marks)

• How would B be obtained from a named alcohol?

 

 

 

 

 

6.

A mixture of ammonia um chloride and calcium hydroxide was heated in a round bottom flask as shown on the diagram above. The gas produced was dried and passed over heated copper (ii) oxide in a tube.

1. a) Write the equation for the reaction in the round bottom flasks ……… (2marks)

1. Identify

 (i) The gas………………………….

(ii) The drying agent………………………………… (2marks)

1. State any color change that would be observed

In the heated tube………………………………. …… (1 mark)

1. Give the products formed when the gas is passed over heated copper (II) oxide….. .(3marks)

2. Give two large scale uses of the gas produced (2marks)

 

 

 

SECTION B

Answer any two question in this section. All questions carry equal marks.  Where appropriate, equations and diagrams should be given to clarify your answer. Write your answers on the lined s which follow this section. Useful data will be found on the back.

7.

Give an account of an experiment you would

carry out to determine the heat of combustion of methanol (your description should end with the collection of data) Carrying out such an experiment it was found that temperature of the 200cm³ of water was raised from 20°C to 75°C when 2.10g of methanol was completely burnt. Use the data above to determine the heat of combustion of methanol           (25marks)

 

 

6. Briefly describe how aluminum and iron can be

Extracted from their ores. For each metal give two large scale uses (25marks)

 

 

7. Describe the type of bonding that exists in each of the following substances:

Magnesium chloride, Carbon dioxide and Calcium. Give two physical properties of each substance and relate each property to the type of bonding found in the substance

 

 

 

10.

               Cu_(g) +4HN0_{3(aq —————————->}     Cu(N0₃)_{2(aq) +}2N0_2(g) + 2H₂0

              NaOH(aq)  + HCl(aq)  ———–à NaCL(aq) +  H₂0(l)

             BaCL2(aq)  + K2SO4 ————————à BaSO4(s) + 2KCL(aq)

The three equations given above represent three different

Methods of preparing salts in the laboratory. In each case describe

how a pure solid sample of the salt in bold print indicated in the

Equation can be obtained from the given starting substances

(25marks)