YEAR 9 CHEMISTRY MARKING SCHEME

[Pages:6]DEPARTMENT FOR CURRICULUM, LIFELONG LEARNING AND EMPLOYABILITY Directorate for Learning and Assessment Programmes Educational Assessment Unit

Annual Examinations for Secondary Schools 2021

Track 3

YEAR 9

CHEMISTRY

MARKING SCHEME

Item

1 a b c d e f g h

Answer and guidelines Section A

Liquid. E Boiling. 1500 1500 Tightly packed; strong forces of attraction between them; vibrating. This sample of iron is impure. Chemical.

Total

Marks

1 1 1 1 1 1 1 1 8

2 a b

False statements:

Elements can be split up into simpler substances by chemical methods.

1

Most elements are liquids or gases at room temperature.

1

Any two of:

? Shiny when freshly cut

? Good conductors of heat and electricity

? Relatively high melting point

? Relatively high density

2

? Malleable (can be hammered)

? Ductile (can be drawn into wires)

? Usually solid at room temperature

? Most metals are sonorous or make a bell-like sound when struck

Accept other suitable answers.

c i

1 mark for electron arrangement. 1 mark for number of protons in nucleus. 3 1 mark for number of neutrons in nucleus.

1 mark for electron arrangement.

ii

2

1 mark for charge.

Chemistry ? Marking Scheme ? Year 9 ? Track 3 ? 2021

Page 1 of 6

Item iii

d i

ii

iii e i

ii

Answer and guidelines

Ionic (electrovalent).

Diatomic elements exist as molecules composed of only two atoms of the

same type of element.

H2 + Cl2 2HCl

1 mark for formulae.

1 mark for balancing.

Covalent.

115B has one neutron more than 105B.

115B

Total

Marks 1 1

2

1 1 1 16

3 a i blue, CuSO4.5H2O

1,1

ii Calcium carbonate or CaCO3

1

b

C3H8 + 5O2 3CO2 + 4H2O

1

1 mark for drawing oxygen atoms

joined correctly.

1 mark for showing correctly shared

c

3

electrons.

1 mark for correct number of electrons.

Accept atoms touching each other.

d

Ozone protects the Earth's surface from excessive solar U.V. radiation

1

which causes cancer in living things.

Total 8

4 a

Check boiling point / melting point / density.

1

b i deliquescent.

1

ii efflorescent.

1

Sodium. c

1 Accept formula or other suitable answers.

Mg (s) + H2O (g) MgO (s) + H2 (g)

d

1 mark for formulae. 2

1 mark for balancing.

e

Chlorine.

1 Accept Cl2 or other suitable answers.

KOH f

Accept name or other suitable answers. 1

Sulfur dioxide. g

1 Accept formula.

h

Carbon monoxide.

1 Accept formula.

Total 10

Page 2 of 6

Chemistry ? Marking Scheme ? Year 9 ? Track 3 ? 2021

Item 5 a

b c d e

f

Answer and guidelines

A: Thistle funnel.

B: Gas jar.

C: Beehive shelf.

Zn + 2HCl ZnCl2 + H2

1 mark for formulae.

1 mark for balancing.

Expose the gas to a lighted wooden splint, gas burns with a `pop' sound.

To introduce the dilute acid into the reaction flask in a controlled manner.

OR Prevents the gas produced from escaping.

Hydrogen is insoluble in water.

Moles of Mg atoms = 92.31 / 24 = 3.85

Moles of H atoms = 7.69 / 1 = 7.69

Marks 1 1 1

2

1 1 1

1

Ratio Mg : H = 3.85 : 7.69 Divide by 3.85 to simplify ratio = 1 : 2 Empirical formula = MgH2

1 Total 10

6 a i strong; weak

2

neutralisation; soluble; hydroxide ii

Accept OH- instead of hydroxide.

3

sodium hydroxide solution: 13

sodium chloride solution: 7

dilute hydrochloric acid: 1

b

vinegar: 3

3

clean rainwater: 5/6

acid rain: 3/4

Do not accept values greater than 4.

? mark each.

Total 8

SECTION B

7 a i Sulfuric acid.

1

H2SO4 (aq) + Fe(OH)2 (s) FeSO4 (aq) + 2H2O (l)

1 mark for formulae.

ii

3

1 mark for balancing.

1 mark for state symbols.

iii To ensure all the acid has reacted.

1

iv If all the acid is used, the litmus paper should remain blue.

1

To prevent the formation of anhydrous iron(II) sulfate.

1

v A slower rate of evaporation allows for the formation of large hydrated

1

crystals.

Chemistry ? Marking Scheme ? Year 9 ? Track 3 ? 2021

Page 3 of 6

Item vi

Answer and guidelines

Marks

water bath tripod

1 mark for evaporating dish. 1 mark for drawing water bath.

1 mark for drawing tripod & Bunsen burner. 3

Deduct ? mark for each missing label.

b i Sodium hydrogen sulfate, NaHSO4

1

ii Acid salt.

1

c i Precipitation.

1

ii RFM Fe2(CO3)3 = (56 ? 2) + (12 ? 3) + (16 ? 9) = 292

1

73 / 292 = 0.25 moles

1

RFM FeCl3 = 56 + (35.5 ? 3) = 162.5

Fe2(CO3)3 : FeCl3 = 1 : 2

1

iii 292 g Fe2(CO3)3 would require (162.5 ? 2) g FeCl3

73 g Fe2(CO3)3 would require ? g FeCl3 (allow follow through)

1

(162.5 ? 2 ? 73) / 292 = 81.25 g FeCl3

(allow follow through)

1

iv Wash the residue (insoluble salt) with distilled water.

1

Total 20

8 a b

Manganese(IV) oxide. Catalyst. Hydrogen peroxide. H2O2

Accept any other reasonable answer. 1 1 1 1

c

Page 4 of 6

5

Trough

1 mark for drawing apparatus. 1 mark for correct assembly of apparatus. 3 marks for correct labelling of apparatus and chemicals.

Chemistry ? Marking Scheme ? Year 9 ? Track 3 ? 2021

Item d

e

Answer and guidelines

2H2O2(aq) 2H2O(l) + O2(g)

1 mark for formulae.

1 mark for balancing.

1 mark for state symbols.

RMF of Fe2O3 = 160 RMM of 3H2O = 54

1 mark for molar masses.

Total mass of 1 mole Fe2O3.3H2O = 214 g = 100% mass of 3H2O = 54 g = ?

1 mark for working.

Answer = 25.23%

1 mark for answer.

Marks 3

1

1 1

Method

Example of use

galvanising

car body

oiling f

painting

car engine 5

bridge

sacrificial protection

iron ship

plastic coating

wire fence 1 mark for each correct answer.

Total 20

Tear the leaves into very small pieces and place them into a mortar.

1

9 a i Add some alcohol and grind (crush) the leaves with a pestle until the

1

alcohol turns green as the chlorophyll is extracted.

ii Paper chromatography.

1

1 mark for chromatography paper.

1 mark for solvent.

1 mark for spot of chlorophyll.

1 mark for correct assembly of

iii

apparatus. 4

Deduct ? mark for each missing

label.

Accept alternative correct setups such as using a round chromatography

paper with a central spot of chlorophyll.

The four components of chlorophyll will separate by travelling different

1

distances from the base line up the paper.

iv

Carotenoids will travel the furthest distance.

1

Chlorophyll b will travel the least distance.

1

Fractionating column used in fractional distillation only.

1

b

Simple distillation is used to obtain the pure solvent from a solution. Fractional distillation is used to separate mixtures of miscible liquids

1 1

based on their different boiling points.

Chemistry ? Marking Scheme ? Year 9 ? Track 3 ? 2021

Page 5 of 6

Item c i

ii iii

Answer and guidelines

Mass of water removed = 4.92 ? 2.40 = 2.52 g

RMM of H2O = (1 ? 2) + 16 = 18

18 g = 1 mole H2O

2.52 g = ?

2.52 / 18 = 0.14 moles

RFM MgSO4 = 24 + 32 + (16 ? 4) = 120

120 g = 1 mole MgSO4

2.40 g = ?

2.40 / 120 = 0.02 moles

Ratio MgSO4 : H2O = 0.02 : 0.14

Simplify ratio

1 : 7

Formula = MgSO4.7H2O x = 7

Marks 1 1

1 1

1

1 1 Total 20

Page 6 of 6

Chemistry ? Marking Scheme ? Year 9 ? Track 3 ? 2021

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