KIMIA SPM 2001

TECHNIQUE OFANSWERING SPM CHEMISTRYDisediakan oleh Chong Pei Si

(I) Mistakes in drawing diagrams

WrongCorrectWrongCorrect

1 H H H

H C C C H

OH H H

2

3

4

II Describing colours Fail to mention the initial colour when there is a colour change

Inaccurate/IncorrectCorrect

Clear (solution)

Purple colour disappears Solution turns colourlessPotassium mangnate (Vll) is decolourise

Product of electrolysis at the cathode:

Copper is formed

Brown precipitate seen

Titration : Pink NaoH turns colourless

Bromine water is decolourised

Electrolysis : Blue copper (II) sulphate turn colourless

III.Writing equations1. Equation not balanced Eg: Na + O2 (Na2O2. Cannot differentiate between Ionic equations : Zn + 2H+ ( Zn2+ + H2 Half equations : 2H+ + 2e ( H2 Zn ( Zn2+ + 2e Chemical equations (complete equations) 2HCl + Zn ( ZnCl2 + H2 3. Do not write WORD EQUATIONS 4. Do not use symbol or formulae in answering structured and essay questions. (except for ions or in diagrams)

Example of Important Chemical EquationsReactionExampleBalanced chemical equationIonic Equation

1Metal + AcidMagnesium + Hydrochloric acid

2Neutralisationsodium hydroxide + sulphuric acid

3DisplacementZinc + Copper (II) sulphate

4Precipittation reactionsilver nitrate + potassium chloride

5Metal Carbonate + AcidCalcium carbonate + hydrochloric acid

(IV) Chemical Tests

Incorrect

1Confirmatary test of oxygen gas

Test with a glowing splinter

2Confirmation test of H2 gasPlace the glowing wooden splinter to the test tube contains gas

3 Confirmatary test of carbon dioxide gas Use lime water

4Test for Fe2+ ions

Add sodium hydroxide into a test tube

V Incomplete/Inaccurate statements or phrases.Sample QuestionsIncorrect answerCorrect answer

1. Define proton number- Positive charge particle in the atom

- the number of proton

1. Explain why argon is exist in monoatomic gas- The outer most shells of argon is full - Stable electron arrangement

2. Explain Neon is chemically inertNeon is chemically inert because it already stabile

3. Sodium located in group 1 and period 3 in periodic tableSodium atom has 1 valence electron and

3 shells

4. Describe what happen to chlorine and Aluminiun atom when the atoms form a compoundChlorine received electron to form chloride ion Cl- Aluminium atom loss electron to form Aluminium ion Al3+

5. Explain why temperature does not change when ice melts.

Because the ice is changed from solid to liquid

6. State one similar physical property of group 1 elementsThey are a metals

7. Explain why sodium and potassium elements show similar chemical properties

They are located in the same group in periodic table

8. Group 1 elements react with cold water vigorously. Write a balanced chemical equation for the reaction of potassium with cold water.

2K + H2O K2O + H2

9. How are these metals kept in the laboratory? Give a reason for your answer.

They are kept in paraffin because they are reactive.

10. Plot a graph of the temperature of X against time

Time, s

Temperature, oC

0

70.0

60

77.0

120

83.0

180

83.0

240

83.0

300

84.0

360

89.0

420

95.0

(a) Based on the graph in (a), what is the melting point of X? Show how you get the answer.

83

11. Give one chemical property of the covalent compound

An covalent compound can not conduct electricity

12. Give one chemical property of the ionic compound

It dissolve in water

13.Give one chemical property of the transition element

Transition metals have colour

14. Why ethanol can not conduct electricity

-Ethanol is covalent compound

-Ethanol can not conduct electricity because its do not have free moving ions

15. Observation of electrolysis of CuSO4

Anode : oxygen gas released

Cathode : copper metal is formed

16. Why Mg is terminal negative ( voltaic Cell) ?

Magnesium atom is easier to release

electron because magnesium is more reactive

17. What is effect of concentration of solution to the rate reactionWhen the concentration higher, the rate of reaction will be faster

18. Why covalent compounds have low melting pointAttractive forces between molecules are small /lower

19. Explain why electrolyte can conduct electricity in molten state but not in soli stateThe ions in the electrolyte can move

20. Why HCl is an acid ?

An acid contain hydrogen ion

21. What is alkali.An alkali is a substance that contains oxide/hydroxide ions

22. State the observation at anode when electrolysis of 0.01moldm-3 of HCl Hydrogen gas is released

23. Compare the properties of ionic and covalent compoundionic compounds have high boiling point/melting point, can dissolve in water and conduct electricity in molten or aqueous form.

24. What is hydrocarbon compound ?A Hydrocarbon is a compound that contains carbon and hydrogen.

25. Important statement in rate of reactionFast reaction Slow reaction

Rate of reaction getting slower

Smaller size particles has a bigger surface area

High concentration of acid contain of more particles

The collision between particles increase cause the rate of reaction also increase

When the temperature is increased, the number of collisions also increases

solution

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