SULIT14541/2/PP
4541/2/PP
Peraturan Permarkahan
Chemistry
Kertas 2
Okt/Nov 2012
MPSM PAHANG
PEPERIKSAAN PERCUBAAN SPM TAHUN 2012
TINGKATAN 5
CHEMISTRY
Kertas 2
PERATURAN PEMARKAHAN
______
Kertas skema ini mengandungi 10 halaman bercetak
MARKING SCHEME / SKEMA PERMARKAHAN
CHEMISTRY PAPER 2
TRIAL SPM MPSM PAHANG 2012
NO / Answers / Marks1.a)
b)(i)
(ii)
c)
d)(i)
(ii)
e)(i) / C3H6
CnH2n+1 OH
C3H7OH C3H6 + H20
H H H H H H
H- C –C- C - H H – C – C – C -O H
H H H H OH H
Propan-1-ol Propan-2-ol
(any one)
Propane
C3H6 + H2 C3H8
-Formula reactant correct
-Formula product correct
Propyl ethanoate / 1
1
1
1+1
1
1
1
1
9
2.a)
(i)
(ii) / Number of proton in nucleus of its atom
15 / 1
1
b) / Nucleon number / 1
c)(i) / Q and R have different number of neutron/nucleon number / 1
(ii) / Carbon 14 - to estimate the age of fossils and artifacts
Cobalt 60 - kill cancer cells,sterilised medicalinstruments
Sodium 24-detect leakage of underground pipes
(any one) / 1
d (i)
(ii)
iii) / 2.8.7
7
Draw diagram:
- / 1
1
-Figure of electron arrangement of R
3 shells / 1
1
9
3.a)
( i)
(ii)
(iii)
b)
c)
d)
e)
f)
g) / Z
Q
Y
Q, P, Z, Y, T
4
Z has higher number of protons than T. Hence it has stronger nuclei attraction on the electrons.
Y3+
Transition Elements
Their ions or compounds are colored//They form complex ions or compounds/they are good catalysts//They can have variable oxidation. / 1
1
1
1
1
1 + 1
1
1
1
10
4.a)
b.(i)
(ii)
(c)
d)(i)
(ii)
e)
f)
/ H+ , Cu 2+ ,
SO42- , OH -
Bubbles of gas released
Concentration of Cu2+ decrease // Cu 2+ discharge to form Cu atom
Cu2+ + 2e Cu
Anode become thinner / smaller / mass decrease
Cathode become thicker / bigger / mass increase
Correct diagram
Copper electrode at anode
Steel spoon at cathode
Copper (II) sulphate as electrolyte
Correct label
Hydroxide ion / 1
1
1
1
1
1
1
1
1
1
10
5.a)
b)
c)
d)
e)
f)
g) / Pink to colourless
The point in the titration at which the indicator changes colour
H2SO4 + 2NaOH Na2SO4 + 2H2O
Sodium sulphate and water
M1V1 = 1
M2V2 2
0.25 × V1 = 1
0.5 × 25 2
V1 = 1 × 0.5 × 25
2 × 0.25
= 25cm3
50 cm3
i) Vinegar is used to cure wasp sting that alkaline in nature
ii) Toothpaste contain bases to neutralize acid produce by bacteria / 1
1
1+1
1
1
1
1
1
1 + 1
11
6.
a)
b)
c)
d)
e)
f) / Redox reaction is a reaction in which oxidation and reduction occur at the same time
Oxygen and water
Fe → Fe2+ + 2e
Label of water droplet, oxygen and iron
Label of anode and cathode
Draw arrow from negative to positive pole iron
Electron transfer form anode to cathode
Oxygen in water gains electrons
Hydroxide ion is form
Using sacrificial metal // sacrificial protection /
By alloying /
By tin platting /
By galvanizing
(Any two) / 1
1
1
1
1
1
1
1
1
1+1
11
7
a)
b.
(i)
(ii)
c)
d.(i)
(ii)
iii) /
Correct axis with unit
Correct and Smooth line
Correct scale
Pb(NO3)2 + 2KI PbI2 + 2KNO3
Volume of Pb(NO3)2 = 2.5 cm3
No of mole Plumbum (II) ion = 1 x 0.0025 = 0.0025 mol
No of mole iodide ions = 2 x 0.0025 = 0.005 mol
Pb2+ +2 I- PbI2
Correct reactants and products
Balance equation
Salt X = Copper (II) carbonate
Gas Z = Carbon dioxide
Y precipitate = Barium sulphate
CuSO4 + Ba(NO3)2 Cu(NO3)2 + BaSO4
Correct reactants and products
Balance equation
1. Add sodium hydroxide solution.
2. Blue precipitate formed indicates the presence of Cu+ ion.
3. Add hydrochloric acid.
4. Add barium chloride solution.
5. White precipitate formed indicate the presence of SO42- ion. / 1
1
1
1 + 1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
20
8.
a)
(b)(i)
(ii)
(iii)
(iv)
c) (i)
(ii) / 1. the mixture becomes hot
2. the thermometer reading increase
3. zinc powder dissolves
4. brown solid/precipitate formed
5. the blue solution turn colourless
(Any three)
Cu2+ + Zn Cu + Zn2+
-Correct formula & reactants
-correct balance
Heat released in the reaction
-50x4.2x5// 1050 J
-number of mol of Cu atom
50x0.1//0.005 mol
1000
-show the step to obtain heat of displacement
1050 J
0.005 mol
- heat of displacement with unit and negative symbol
-210000 Jmol-1//-210 kJmol-1
-heat loss to the surrounding
2 precautions
1. use polysterene cup//use two layers of polysterene cup
Instead of one.
2. add zink powder quickly into the solution
3. stir the mixture continuously until highest temperature
obtained.
(Any two)
- temperature change will be doubled//100C
- number of copper(II) ions per unit is doubled/ two times
higher
Label Energy, correct level of reactants & product
- correct chemical equations
- H with negative symbol and unit
Zn + Cu2+
H= - 210 kJ mol-1
Energy
Zn2+ + Cu
- Exothermic reaction//heat released to the surrounding
- Energy content of reactants is higher than energy content of products
- Heat absorbed to break down the bond is lower than heat released to form a bond
1
1
1
1
1
1
1
1+1
1
1
1
1
1
1
1
1
20
9
a.(i)
(ii)
b.
c. /
- Tomato puree is used as a colouring agent to restore the colour of the food.
- Sugar // spice is used as a flavouring agent to enhance the taste of food
- Permitted modified starch is used as thickener to thicken food.
Advantage :
i) to prevent food from spoilage
ii) to improve appearance, texture or taste
Disadvantage:
i) Lead to serious diseases like asthma, and cancer
-Part A is hydrophobic:Soluble in oil or grease
-Part B is hydrophilic: Insoluble in oil or grease//soluble in water
- Hard water contain Mg2+ and Ca2+ ion
- Detergent does not form scum in hard water
- Soap form scum in hard water
- Mg2+ and Ca2+ in hard water react with soap
- Soap molecule consist of hydrophobic and hydrophilic part
- Hydrophobic part dissolve in oil
- Hydrophilic part dissolve in water
- During scrubbing/rinsing the oily stains/spots is washed away
- Cloth in experiment II /detergent is cleaner than cloth in experiment I
- Detergent in hard water is more effective than soap.
1
1
1 + 1
1 + 1
1
1
1
1
1
1
1
1
1
1
20
10.
a.(i)
(ii)
b)
c) / The speed at which reactant are converted into product in a chemical reaction// change in selected quantity of reactant or produrt per unit of time taken.
Total surface area / concentration of reactant / temperature of reactant / use of catalyst / pressure of gaseous reactant
(any 4)
To make the coffee powder and sugar dissolve easier in water.
The heat given to the water will give more kinetic energy to the particles.
The particles of water, coffee powder and sugar move faster.
They will collide each other more frequent.
The frequency of effective collision will increase.
Precipitate : Sulphur
Materials:
0.2 mol dm-3 sodium thiosulphate, 1.0 mol dm-3 sulphuric acid, a piece of white paper marked ‘X’ at the centre.
Apparatus:
150 cm3 conical flask, stopwatch, 50 cm3 measuring cylinder, 10 cm3 measuring cylinder, thermometer, Bunsen burner, wire gauze.
Procedure:
Using a measuring cylinder, 50 cm3of 0.2 mol dm-3 sodium thiosulphate solution is measured and poured into a conical flask.
The conical flask is placed on top of a piece of white paper marked ‘X’ at the centre.
5 cm3 of 1.0 mol dm-3 sulphuric acid is measured using another measuring cylinder.
The sulphuric acid is poured immediately and carefully into the conical flask. At the same time, the stop watch is atarted
The mixture in a conical flask is swirled.
The ‘X’ mark is observed vertically from the top of the conical flask through the solution.
The stopwatch is stopped once the ‘X’ mark disappears from view.
Step 1 – 7 are repeated using 50 cm3 of 0.2 mol dm-3 sodium thiosulphate solution at 40oC, 50oC, 60 oC by heating the solution before 5 cm3 of sulphuric acid is added in.
(Max 8)
Conclusion
The increase of temperature, increase the rate of reaction / 1
1+1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
20
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