POK OI HOSPITAL TANG PUI KING MEMORIAL COLLEGE

FIRST TERM TEST ( 1997-1998 )

S5  CHEMISTRY

Class                :           ________________                Date     :           __________________

Name               :           ________________                Time allowed: 60 minutes

Class Number  :           ________________                ( P.1 - P.5 /38 )

Instructions to students:

1. Answer ALL questions.

2. Write your answers on the foolscap papers provided.

3. The total score is 100 marks.

Section A ( 40 % )

1. An acid is a substance that

    A. is made up of hydrogen ion(s) and other anion(s).

    B. dissociates to give hydrogen ion(s) in its pure form.

    C. neutralizes with an alkali to form salt and water only.

    D. contains hydrogen atom covalently bonded to an oxygen atom.

2. Vinegar is a weak acid because

    A. it contains very small amount of ethanoic acid.

    B. it has a pH value smaller than 1.

    C. the ethanoic acid in vinegar ionizes slightly in water.

    D. it ionizes to a greater extent in organic solvents.

3. Which of the following is alkaline?

    A. Milk of magnesia

    B. Orange juice

    C. Seven-up soft drink

    D. Aspirin

4. Which of the following statements is INCORRECT?

    A. A strong acid is fully ionized in its aqueous solution.

    B. A weak acid is a solution of low concentration.

    C. Aqueous ammonia is a weak alkali.

    D. Sodium hydroxide is a strong alkali.

5. Both 1M hydrochloric acid solution and 1M ethanoic acid solution

    A. have the same concentration of hydrogen ions.

    B. have pH values below 7.

    C. have the same electrical conductivity.

    D. give the same colour with universal indicator solution.

6. What mass of ethanoic acid ( CH₃COOH ) has to be weighed out to prepare 250 cm³

    of a 0.4 M solution?

   ( Relative atomic masses: H = 1, C = 12, O = 16 )

    A. 3 g

    B. 6 g

    C. 9 g

    D. 12 g

7. Which of the following matching of apparatus and name is correct?

8. How many cm³ of 0.2 M hydrochloric acid is required to react completely with

    25.0 cm³ of 0.1 M sodium carbonate solution?

    A. 12.5 cm³

    B. 25.0 cm³

    C. 50.0 cm³

    D. 75.0 cm³

9. Which of the following substances will react with concentrated nitric acid to give a

    brown gas?

                        (1) Mg (s)

                        (2) Cu (s)

                        (3) Fe (s)

    A. (1) only

    B. (2) only

    C. (1) and (3) only

    D. (1), (2) and (3)

10. The best method to prepare sodium nitrate is to add

    A. sodium metal to nitric acid.

    B. sodium metal to copper(II) nitrate solution

    C. sodium chloride solution to nitric acid.

    D. sodium carbonate to nitric acid.

Section B ( 60 % )

1. (a) The energy source of country A is shown below.

        (i)    What is the value of x?

        (ii)   Suggest TWO ‘others’ energy sources.

        (iii)  The three energy sources listed above are non- renewable. What is the

                difference between ‘renewable’ and ‘non- renewable’ energy sources? Give an

                example of renewable energy sources.

     (b) (i)    Complete the following table.

        (ii)   What are the two products of burning hydrocarbons in a sufficient supply of

                oxygen?

        (iii)  Write a balanced equation for the burning of butane in a sufficient supply of

                oxygen?

( 12 marks)

2. (a) Explain why magnesium gains in mass but coal loses mass when each is burnt in

         air.

     (b) The diagram below shows an incomplete Fire Triangle:

         (i)    What is the missing part of the Fire Triangle?

         (ii)   What are the requirements of fire fighting?

    (c) To put out fire in a pan of cooking oil, a housewife poured water on the pan.

          (i)    Suggest why the housewife poured water on the pan.

         (ii)   Why is it inappropriate to use water to put out the fire?

         (iii)  Suggest a proper action to deal with this domestic accident. Explain your

                 answer briefly.

     (d) A small child has been playing matches and his clothes have caught fire. Explain

         how you would put out the fire.

( 14 marks )

3. Petroleum is a mixture of hydrocarbons. The diagram below illustrates one part of an

    industrial plant that provides us with important energy sources and chemicals:

    (a) (i)    What is the part of the industrial plant called?

         (ii)   Name the industrial process taking place and state its importance.

    (b) (i)    Give ONE example of a product at each of the four outlets, A, B, C and D.

         (ii)   Why do different products come out at different levels?

    (c) Apart from differences in appearance and boiling points, state TWO other

         properties you would expect the products in (b) to differ from each other.

         Give ONE reason to account for all the differences.

    (d) Draw a labeled diagram to show how you would obtain similar products on a test-

         tube scale in the laboratory.

    (e) The product obtained at A is often cracked to give some smaller molecules.

         Give TWO advantages of this process.                            ( 19 marks )

4. The production of Hong Kong Town Gas is shown below schematically:

    (a) (i)    Name the process by which naphtha is obtained from crude oil.

         (ii)   State the approximate number of carbon atoms in naphtha.

     (b) (i)    Name the process in which naphtha reacts with steam to produce town gas.

         (ii)   Suggest the catalyst which can speed up the production of town gas in the

                 reactor.

     (c) Name TWO major components in town gas.

     (d) In the purifier, hydrogen sulphide present in the gaseous mixture is removed.

          Explain why this is necessary.

     (e) (i)    After purification, extra naphtha and air are added to town gas.

                 What are their functions respectively?

         (ii)   Why is an odorant required to warn consumers against leakage of town gas?

     (f) State TWO potential hazards associated with the use of town gas.

     (g) It is suggested that coal gas should replace naphtha in the production of town gas.

         Suggest ONE advantage for this.

     (h) If you suspect a leakage of town gas in your home, explain why

         (i)    you should open all the windows at once

         (ii)   you should not use your telephone to call for help.        ( 15 marks )

END OF PAPER