[4541/1] [4541/2] chemistry - wordpress.com...... chemistry [4541/2] answers- paper 1 chemistry ...

SOALAN ULANGKAJI SPM 2017

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No Answer1 C2 D3 D4 C5 D6 C7 B8 B9 C

10 A11 D12 C13 C14 C15 B16 C17 B18 C19 A20 C21 B22 B23 B24 C25 B

No Answer26 D27 B28 B29 B30 D31 C32 B33 A34 B35 C36 C37 B38 B39 C40 B41 C42 B43 D44 D45 B46 D47 A48 C49 C50 B

Chemistry[4541/1][4541/2]

Answers- Paper 1 Chemistry

https://cikguadura.wordpress.com/


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No. Answer SubMark

TotalMark

1 (a) [able to state the number of valence electrons of phosphorus] 4

(b) (i) [able to state the type of bond correctly] Example: Covalent bond (ii)

1st mark: - showing the sharing of electrons and correct number of electrons in each shell

2nd mark – correct label and correct number of electron pairs being shared

(c) [able to explain ] Example: weak forces of attraction between molecules/ particles

(d) (i) [able to write correct chemical formula] Example:MgQ2

(ii) [able to write correct and balance chemical equation] Example: Mg + Q2 → MgQ2

(iii) [able to show the calculation correctly]

1st mark no of mole of Mg= 6/24 = 0.25 mol

2nd mark Volume of florine needed = 0.25 x 22.4 dm3/ 5.6 dm3

1

1

1

1

1

1

1

1

1

1

1

1

1

2

1

2

2

Total 9

CHEMISTRYPAPER 2ANSWERSSECTION A

S

H



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No. Answer SubMark

TotalMark

2 (a) (i) [able to state the meaning of polymer] Long chained molecules / large molecules / macro-molecules made up of many smaller repeating units / monomers.

(ii) [able to list one correct property] Does not rust / lighter / cheaper

(iii) [able to draw the repeating structural formula correctly]

(b) (i) [able to list the correct substance] Steel

(ii) [able to list one correct property] Can withstand higher pressure / support heavier loads / stronger / higher tensile strength

(c) (i) [able to list one correct property] Does not corrode / does not react with the preserved food / glass is chemically inert/ glass is non-reactive

(ii) [able to name the correct type of glass] Soda lime glass

(iii) [able to list all the compounds in the substance correctly] Silicon dioxide / silica / sodium silicate

[able to one name the correct type of glass ] Sodium oxide and calcium oxide / calcium silicate

(d) (i) [able to name correct type of ceramic] Brick / tiles

1

1

1

1

1

1

1

1

1

1

1

1

1

1

1

4

1

Total 10

H H

C C

H H n


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No. Answer SubMark

TotalMark

3 (a) [able to state the defination correctly] Empirical formula shows the simplest ratio of atom of each element in a compound.

(b) [able to state the apparatus correctly] Crucible

(c) [able to name a correct metal and to explain ] magnesium / aluminium / calcium It is reactive towards oxygen gas

(d) [able to list two precautions correcly] 1. Metal M strip is polished with sandpaper. 2. The crucible lid is opened and closed at interval. 3. The heating, cooling and weighing process is repeated until the crucible and its content show a constant mass (Any two answer)

(e) [able to show the calculation correctly]

Empirical formula of metal M oxide is MO

1

1

1

1

1

1

1

1

1

1

1

2

1

2

2

3

Total 9

Element M OMass,g 25.25 – 19.85 = 5.4 30.05 – 25.25 = 3.2

Number of mol

5.4 = 0.2 27

3.2 = 0.2 16

Mol ratio 1 1


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No. Answer SubMark

TotalMark

4 (a) (i) [able to state anode and cathode correctly] Example: Anode: W and Y Cathode: X and Z

(ii) [able to name the product that is formed at electrode

W correctly]

Example: chlorine gas

(ii) [able to write a correct and balanced half equation]

Example: 2Cl- → Cl2 + 2 e

(b) (i) [able to state the observation at electrode Y correctly] Example: colourless bubles gas

(ii) [able to name the product correctly]

Example: oxygen gas

(iii) [able to state a confirmatory test correctly]

Example:

Put a glow spinter inyo the test tube,

Glowing splinter ignited.

(c) (i) [able to state the product that will formed at electrode W] Example: oxygen gas

(ii) [able to explain the factor of concentration ions in solution]

Example :

The hydroxide ions is lower than nitrate ion in ECS

11

1

1

1

1

1

1

1

1

4

4

2

Total 10


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No. Answer SubMark

TotalMark

5 (a) [able to state the process correctly] fermentation

(b) [able to draw the correct structural formula of compound X]

(c) (i) [able to write the general formula for the homologous series of compound Y] CnH2n

(ii) [able to name the product correctly] Deliver compound Y / ethene into bromine water / potassium manganate(VII) solution Brown colour of bromine water decolourises / changes to colourless / purple colour of potassium manganate (VII) decolourises / changes to colourless

(d) (i) [able to name the functional group of compound Z] Carboxyl group

(ii) [able to write a balance chemical equation] C2H5OH + 2[O] → CH3COOH + H2O

(iii) [able to name the reagent] acidified potassium manganate(VII) / acidified potassium dichromate (VI) solution

(e) (i) [able to identified the reagent use for peparing ethyl propanoate from compound X] Propanoic acid to compound X / ethanol

(ii) CH3COOC3H7

1

1

1

1

1

1

1

1

1

1

1

1

1

2

1

1

1

2

Total 10

H H

H

H

HCC

O H


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No. Answer SubMark

TotalMark

6 (a) [able to state the colour of sulphur correctly] Example: Light Yellow

(b) [able to explain how to measure a fixed quantity of sulphur produced correctly] 1. A piece of white paper marked ‘X’ was placed under the conical flask 2. Time taken for enough sulphur to produce and cover the mark ‘X’ until it disappear from sight

(c) (i) [able to calculate the correctly ]

Example:

(ii) [able to draw the graph correctly] 1. both axes are labelled correctly 2. All 5 points transferred correctly

(d) (i) [able to state the relationship correctly] Example: When the temperature increases, the rate of reaction increases

(ii) [able to explain using the collision theory correctly] Example: 1.Increase in temperature increases the kinetic energy of thiosulphate ion / particles // Thiosulphate ion move faster 2.Frequency of collision between thiosulphate ion and hydrogen ion increases. 3.Frequency of effective collision increases

1

1

1

1

11

1

1

11

1

2

1

2

1

3

Total 10

1time

0.030 0.042 0.053 0.063 0.0711

time (s -1)


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Graph for question 6

50

40

30

20

10

0.020 0.030 0.040 0.050 0.060 0.070

1time (s -1)

Temperature / ° C


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No. Answer SubMark

TotalMark

7 (a) (i) Group 1 and period 4

(ii) Element P - Force of attraction between nucleus and valence electron of atom P is weaker than atom X. - Atom P is easier to relese electron

(ii) -Atomic size of atom Q is smaller

-The positive charge /the number of proton in the nucleus of atom R is bigger

-Force of attraction between the nucleus and the electrons in atom R is stronger

= The electrons are pulled closer to the nucleus

(b) (i) Oxide of A: Basic because oxide of A react with acid only to form salt and water

Oxide of D: Amphoteric because oxide of D react with both acid and base to form salt and water.

Oxide of E: Acidic because oxide of E react with base only to form salt and water. A: Sodium/Magnesium D: Aluminium E: Silicon/Sulphur/Chlorine/Phosphorus

(ii) Na2O + 2HNO3 2 NaNO3 + H2O // MgO + 2HNO3 Mg(NO3)2 + H2O

(iii)

2 1

11

1

1

1

1

1+1

1+1

1+1

1

11

1+1

2

3

4

2

2

2

32

Total 20

SECTION B


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No. Answer SubMark

TotalMark

8 (a) (i) [able to give the following information] - CH3OH + 3/2 O2 → CO2 + 2 H2O - C2H5OH + 3O2 → 2CO2 + 3H2O

- Heat is given off during the formation of carbon dioxide from carbon and water from hydrogen - The number of moles of carbon dioxide and water formed from combustion of ethanol is more than the combustion of methanol

(ii)

Both axes correctly labelled Straight line with positive gradient

(b) (i) [able to explain the meaning of heat of precipitation by

using silver choride as an example]

- Ag+ + Cl- → AgCl

1. The heat of precipitation of silver chloride is the heat

given out.

2. 1 mol of siver chloride is formed from 1 mol of silver ion

and 1 mol of chloride ion

11

1+1

1

11

1

1

5

2

2


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No. Answer SubMark

TotalMark

8 (b) (ii) [able to describe an experiment to determine the heat of precipitation of silver chloride]

Diagram :

Labelled suitable functional apparatus (bottle or cup silver nitrate and sodium chloride solution Procedure : 1. (20 – 100) cm3 of (0.01- 2.0) mol dm-3 silver nitrate solution is measured and pour into a plastic cup and the initial temperature, T1 is recorded. 2. (20 – 100) cm3 of (0.01- 2.0) mol dm-3 sodium chloride is measured and the initial temperature, T2 is recorded. 3. Sodium chloride solution is quickly poured into the plastic cup containing silver nitrate solution. 4.The mixture in the cup is stirred using the thermometer. 5.The highest temperature is recorded. Results : [ for 25cm3 solution and 0.5 mol dm - 3 concentration] Initial temperature of reactants mixture = (T1 + T2) / 2 = T Highest temperature recorded = T3 Temperature increase = T3 – T1 Heat change = mc ϴ = 50 x 4.2 x (T3 - T1) J = a J Number of moles of silver chloride formed = (25 x 0.5)/ 1000 = b mol Heat of precipitation of silver chloride = a/b J mol-1

1 1

1

1

11

11

1

1

...12(max 11)

Total 20

silver nitrate solution + sodium chloride solution

thermometer

plastic cup


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SECTION C

No. Answer SubMark

TotalMark

9 (a) (i) 2SO2 + O3 → 2SO3 SO3 + H2SO4 → H2S2O7 H2S2O7 + H2O → 2 H2SO4

(ii) Temperature of the reaction in Stage II is 450-550 oC The pressure required is 1 atmosphere Vanadium(V) oxide is used as a catalyst

(iii) SO3 has a very low solubility in water When SO3 dissolves in water, a lot of heat is produced.

(b) (i) A composite material is a structural materials made from two or more constituent materials with different properties. (ii) 1. Fibre glass is made from long glass fibres mixed with plastic resin as the binding material. 2. Glass is hard, strong but relatively brittle. 3. Plastic is light, flexible but not strong.

4. Fibre glass is strong, light and flexible.

(c) Pure copper

• The atoms are of the same size and arranged in an orderly manner • The layers of atoms slide over one another easily when a force is applied

Brass

• The copper atoms and zinc atoms in its lattice structure. • The presence of zinc atoms of different size disrupts the orderly arrangement of the copper atoms in brass • This makes it difficult for the layers of atoms to slide over • one another when a force is applied.

111

111

11

1

1111

1

1

1

1

1

111

3

3

2

1

4

7

Total 20


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No. Answer SubMark

TotalMark

10 (a) (i) [able to give a suitable example to explain the meaning of redox reaction in term of change in the oxidation number]

Example : Mg + Zn Mg2+ + Zn / reaction between magnesium and zinc ion // zinc solution

-Redox reaction is a reaction in which oxidation and reduction occur at the same time -Oxidation number of magnesium increases from 0 to +2. Therefore magnesium undergoes oxidation. -Oxidation number of Zn decreases from +2 to 0. Therefore zinc ion undergoes reduction.

(b) [able to write a correct and balanced chemical equation and give explanation] Example :

Ba(NO3)2 + ZnSO4 → BaSO4 + Zn(NO3)2

Ba(NO3)2 + ZnSO4 → BaSO4 + Zn(NO3)2

Oxidation no There is no change in oxidation number in Ba2+ ions and Zn /S/N/O (name at least 2 species)

(c) (i) [able to give suitable examples for the reagent and explain the observation using the correct chemical equation ]

Example : - Reagent X is any oxidising agent : chlorine water/ bromine water/potassium manganate(VII)/ potassium dichromate(V) - Iron(II) ions which are green change to iron(III) ion which are brown - Iron (II) ions are oxidized to iron (III) ions / an iron (II) ion loses one electron / oxidation number increases from +2 to +3 Cl2 + 2 Fe2+ → 2 Cl- + 2 Fe

1

1

1

1

1

1

1

1

1

1

4

3

2+

2+

+2

+5

-2 +2

+6

-2 +2

+6

-2 +2

+5

-2

3+

2+


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No. Answer SubMark

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10 (c) (ii) [able to give a suitable example for metal Y and explain the observation correctly by using a chemical equation] Metal Y is any metal that is more electropositive than copper : zinc/ magnesium/ aluminium. Copper (II) ions which are blue change to copper metal which is brown Copper(II) ions are reduced to copper(II) atoms / a cooper (II) ions receives two electrons / oxidation number de creases from +2 to 0

Mg + Cu + → Mg + + Cu

(d) [able to give a suitable metal that can acts as a sacrificial metal and explain how corrosion of iron can be prevented by using the sacrificial metal] Sample answer: Name any metal which is more electropositive than iron such as zinc/magnesium. Zinc is more electropositive than iron. Zinc is oxidized to zinc ion by losing 2 electrons Zn → Zn2+ + 2e Iron atoms are not oxidized/do not lose electrons

1

1

1

1

1

111

8

5

Total 20

2+ 2+

END OF ANSWER SCHEME


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