· pdf file94 jawapan ulangkaji spm 2015 soalan boleh didapati di laman web times answer...

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93 JAWAPAN ULANGKAJI SPM 2015

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Chemistry[4541/1][4541/2]

TIMES ANSWER PAPER 1 CHEMISTRY SPM

1 C 2 A 3 B 4 D 5 D 6 A 7 A 8 A 9 A 10 D 11 C 12 B 13 D 14 A 15 D 16 B 17 A 18 B 19 A 20 A 21 B 22 D 23 C 24 B 25 D 26 D 27 A 28 B 29 A 30 A 31 C 32 D 33 A 34 C 35 A 36 D 37 C 38 C 39 A 40 B 41 B 42 D 43 B 44 A 45 B 46 C 47 C 48 C 49 D 50 B



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TIMES ANSWER PAPER 2 CHEMISTRY SPM

Question Mark scheme Sub mark

Total mark

1 (a) Compound A and Compound E. They have the elements carbon and hydrogen only and with single bonds between all carbon atoms.

1 1

2

(b) Compound B and Compound C. They have the same molecular formula but different structural formulae.

1 1

2

(c) Butan-1-ol 1 1 (d) Compound F 1 1 (e) Compound D 1 1 (f) CH3Cl 1 1 (g) Compound B and Compound C. 1 1 (h) Hydrogenation

Platinum as a catalyst. 1 1

Total 10 2 (a) (i) To make plastic bottles /container

To make plastic bags 1 1

2

(ii)

1

1

(iii) Polyamides 1 1 (b) (i) Hard/ brittle/ electrical insulator/ resistant to chemical

corrosion

1 + 1

2

(ii) Glass: silicon dioxide / silica / SiO2

Ceramic: kaolinite/ aluminosilicate/ Al2Si2O5 1 1

2

(iii) Borosilicate glass 1 1 (iv) Does not melt at high temperatures 1 1 Total 10 3 (a)

1 + 1

2

(b) An alkali is a molecules which dissociates partially in water to produce OH ions of a low concentration.

1 + 1

2

(c) Sodium hydroxide has a higher pH value than ammonia solution. The concentration of OH ions in sodium hydroxide is higher that that of ammonia solution. Sodium hydroxide dissociates completely when dissolved in water, whereas ammonia dissociates partially when dissolved in water.

1 1

1

3



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(d) Dip a glass rod into concentrated hydrochloric acid. Bring the glass rod close to the ammonia gas. Thick white fumes are produced.

1 1

2

(e) Ethanoic acid 1 1 Total 10 4 (a) A: Liquid

B: Solid

1 1

2

(b)

1

1

(c) Particles of Y held together by weak intermolecular forces A small amount of heat energy is required to overcome the forces

1 1

2

(d)

1 + 2

3

(e)

1 + 1

2

Total 10 5 (a) (i) To relieve pain 1 1 (ii) To destroy the growth of bacteria 1 1 (iii) To change the emotions and behaviour of the patients 1 1 (b) (i) May cause bleeding in the stomach 1 1 (ii) Paracetamol 1 1 (c) Codeine 1 1 (d) (i) Test the patient if he is allergic to penicillin 1 1 (ii) Streptomycin 1 1 (iii) Must complete all the dosage given by doctor 1 1 (e) May cause addiction 1 1 Total 10 6 (a) Saponification 1 1 (b) Sodium hydroxide 1 1 (c) To precipitate soap 1 1 (d) Glycerol 1 1 (e) RCOONa 1 1


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(f) It has a hydrophilic part that dissolves in water. It has a hydrophobic part that dissolves in grease.

1 1

2

(g) (i) It forms scum. 1 1 (ii) Detergent

It does not form scum. 1 1

2

Total 10 7 (a) *Brass is harder than pure copper.

*Pure copper has same size of atom. *Arrange in orderly manner *Easily to slide over one another when force is applied Pure copper

*Brass has two types of atoms with different size of atoms ( zinc and copper ) *The presence of zinc atoms of different size disrupts the orderly arrangement of the copper atoms *The layers of atoms do not slide over one another easily when a force is applied

Brass

1 1 1 1 1 1 1 1 1

9

(b) (i) Composite materials are materials made from two or more different constituent materials, When combined, produce a material with characteristics different and superior from the individual components.

1 1

2

(ii) #Concrete is consists of loose stones held with cement. # Concrete is a very strong material and will not compress or shatter even under quite a large compressive force. # Concrete cannot stand tensile loading (If stretched it will break apart easily). # Reinforced concrete consists of concrete strengthened using steel bars. # Reinforced concrete has the ability to resist being stretched as well as being compressed.

1 1 1 1 1

5

(c) Similarities: Hard/ brittle


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Electrical insulator Resistant to chemical corrosion Differences:

Glass Ceramic Transparent opaque Can be melted and remoulded

Can be melted and remoulded

Does not have a melting point

Have very high melting point

1+1

1+1

4

TOTAL 20 8 (a) #Between Y and Z

#Type of compound is covalent compound #Electron arrangement of Y is 2.7 #Electron arrangement of Z is 2.8.4 #Z needs 4 electrons to achieve stable octet electron arrangement 2.8 #Y needs 1 electron to achieve stable octet electron arrangement 2.8.8 #One atom Z share its 4 electron with 4 atom Y to form a compound with the formula ZY4 #Between X and Y #Type of compound is ionic compound

#Electron arrangement of X is 2.8.1 #Electron arrangement of Y is 2.7 #X needs to release 1 electron to achieve stable octet electron arrangement 2.8 #Y needs 1 electron to achieve stable octet electron arrangement 2.8

1 1 1 1 1 1 1 1 1 1 1 1

12 (b) Melting point:

#Melting point of compound (b)(i) is lower than (b)(ii) #Compound (b)(i) is a covalent compound while (b)(ii) is an ionic compound. #Molecules in covalent compound are held by weak force of attraction - van der Waals forces. #Less energy is required to overcome the forces of attraction between the molecules. Hence the melting point is low. #Ions in ionic compound are attracted to one another by strong electrostatic forces between the ions. More heat energy is required to overcome the forces, hence the melting point is high. Electrical conductivity #Covalent bond in (b)(i) consist of molecules which is neutral. It is also not an electrolyte and cannot conduct electricity in both molten and solid state.

1 1 1 1 1 1


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#Ionic compound is electrolyte which conduct electricity in molten state and aqueous solution. #This is because ionic compound contains free moving ions which carry electrical charge.

1 1

8

TOTAL 20 9 (a) Electron arrangement of atom S is 2.8.4

Atom S has 4 valence electron. Hence it is located in Group 14 Atom S has 3 shells occupied with electrons. Hence it is located in Period 3

1 1+1

1+1

5

(b) Electron arrangement of lithium is 2.1 Atomic radius of lithium is smaller than sodium The distance between the nucleus of lithium and the valence electron is nearer/ closer The force of attraction between the nucleus of lithium and the valence electron is stronger Hence the valence electron is more difficult to be released

1 1 1 1 1

5

(c)

Procedure: 1. A small piece of lithium is cut using a knife 2. The oil on the surface of lithium is removed using filter paper 3. Lithium is then placed slowly on the surface of water in a basin 4. The experiment is repeated using sodium. Observation: Lithium moves slowly on the surface of water Name of products: lithium hydroxide and hydrogen Sodium moves rapidly/ faster/ vigorously on the surface of water Name of the products: sodium hydroxide and hydrogen Equations: 2Li + 2H2O ' 2LiOH + H2/ 2Na + 2H2O ' 2NaOH + H2

1 1 1 1 1 1 1 1

1+1

10

TOTAL 20 10 (a) (i) Sodium chloride

Potassium nitrate Ammonium sulphate

3

(ii)

Salt Reactants

Sodium chloride Hydrochloric acid and sodium

hyd oxide

Potassium nitrate

Nitric acid and potassium hydroxide

1 1


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Ammonium sulphate

Sulphuric acid and ammonia solution

2

(b) (i) Method II and method IV

1+1 2

(ii) 2HNO3 + CuO ' Cu(NO3)2 + H2O 2HNO3 + CuCO3 ' Cu(NO3)2 + H2O + CO2

1+1 1+1

4

(iii) 1. Pour 50 cm3 dilute nitric acid into a beaker. 2. Heat to warm the acid. 3. Add copper(II) oxide to the nitric acid slowly and stir. 4. Add until in excess. 5. Filter to separate the excess copper(II) oxide. 6. Heat the filtrate until saturated. 7. Cool the saturated filtrate. Copper(II) nitrate crystals are formed. 8. Filter to separate the crystals. 9. Dry the crystals between two pieces of filter paper (or in the oven).

1 1 1 1 1 1 1 1 1

9

TOTAL 20

END OF MARKING SCHEME


· pdf file94 jawapan ulangkaji spm 2015 soalan boleh didapati di laman web times answer...

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