Paper 2 June 2001

Answer guide for O Level Chemistry (5070/2) – Paper 2 Theory June 2001

A1

Five names at (1) each:

(a )

Aluminium

1

(b)

copper  or or iron

1

(c )

zinc

1

(d)

copper  or or iron

1

(e )

copper

1

A2

Each correct entry to the table (1): Formula

Colour

Cu(OH)2

blue

2

AgCl

white

2

PbI2

yellow

2

BaSO4

white

2

A3(a)(i)

hydrogen is D

1

(ii)

sodium is A

1

(iii)

silicon is B

1

(b)

Name is one of aluminium, lead, tin, zinc

1

A4(a A4(a))

Isot Isotop opes es hav have sam samee no. no. of prot proton onss (sa (same me elem elemen ent) t) with with dif differi fering ng nos. of neutrons: Proton number Nucleon numbers Atomic number Mass number

1

(b)(i)

electrons 2

or same no.

1

(ii)

protons

or same no.

1

(iii)

neutrons 4 and 5

or one more

1

(c )

Helium has a full outer shell Or stable configuration Neither gains nor loses

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Answer guide for O Level Chemistry (5070/2) – Paper 2 Theory June 2001

A5(a)

Reducing agent is iodide (ion) (NOT ( NOT iodine) iodide Because oxid n no. of Cu2+ decreases Or I- gives e-

or

or

or

I-

or

potassium 1

from 2 to 1

Oxidation Number -I —> O

1

(b)

Changes from purple to colourless

1

A6(a)

Diagram 7 dots and 1 cross on each chloride ion

1

Correct charges on all three ions MgCl 0 marks

1

Two physical props from: High m.p. or b.p. or solid Soluble in water  Conducts when molten or in solution

2

(b)

7(a)

Equation: Zn + 2 HCI —> ZnCl2 + H2

(b)

Moles of zinc = 0.65/65 = 0.01

1

Moles of acid = 2x50/1000 = 0.1

1

Refer to 2:1 ratio, hence acid is in excess

1

Rate decreases

1

Concentration of acid is decreasing or surface area of zinc is decreasing

1

(d)

On grid, line is to the left and finishes at 240 cm 3

1

8(a)(i)

series is alcohols

1

(ii)

Mr  is 116

1

(iii)

b.p. is 157 to 162 (unit not required)

1

(iv)

form is CnH2n+1OH

1

(b)

A use, not drinks

(c)(i)

structure ALLOW OH

(c )

or

or

or

ionic equivalent

alkanols

or

CnH2n+2O

1

1 O–H O C

(ii) ii) (iii)

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OH

1

any su suita itable re reagent (e (e.g. ox oxygen, di dichromate(VI), ma manganate(VII) etc )

1

name ethyl ethanoate or acetate

1

structure (e.g. CH3CO2C2H5)

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© UCLES 2002  

Answer guide for O Level Chemistry (5070/2) – Paper 2 Theory June 2001

9(a)

Distillation

1

Crude oil is heated

or

boiled

1

Separate according to b.p. Allow petrol lower b.p.

1

(b)(i)

Carbon monoxide

1

(ii)

Diesel has more SO2

(iii)

Equation: N2 + 2 O2 —> 2 NO2

1

(iv)

CO oxidised to CO2

1

NO2 reduced to N 2

1

(c )

or

CO and/or

NO x

1

Calculation: Mr  of octane is 114

1

1.14g gives 5518/1.14kJ

x 1.14

1

answer. 55.18kJ answer alone (1) mark only; unit required somewhere [max 2]

1

B10( B10(aa)(i) )(i)

etha thanol nol incr increease ases

1

(ii)

exothermic

1

because increase in temp. lowers ethanol

1

(iii)

50 ats and 250˚

1

(b)(i)

name is ethane

1

(ii)

full structure of 1:2-dibromoethane

1

(c)

Structure of poly(thene) Must show single C - C bond and continuation

1

litter or non-biodegradable, not just pollution

1

Correct structure of ethene If not C2H4 then 0

2

(d)

or

equilibrium moves right

If all dots [max 1] 1] If dot & cross between carbons [max 1]

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Answer guide for O Level Chemistry (5070/2) – Paper 2 Theory June 2001

B11(a)

(b)

(c )

(d)

B12(a) (b)(i)

(ii)

Catalyst is Pt

or

V2O5 name or formula

1

Equation correct formulae

1

2 SO2 + O2 —> or

1

⇔

2 SO3 correct balance

Calculation Mr  of acid is 98

1

32g S gives 98g acid

1

196 needs 64 S kg

1

Two uses from: Used to make fertilisers or ammonium sulphate or superphosphate Used to make paints or pigments or BaSO 4 Used to make Dyestuffs Used to make soaps or detergents Used to make fibres or plastics Used to make explosives Used to pickle metals Used as battery acid

2

See fizzing / colourless solution / solid dissolving

1

Names of all three products

1

Colour darkens

1

State changes gas to solid

1

names of products potassium chloride bromine

1

ionic equation Cl2 + 2 Br - —> 2 Cl- + Br 2

1

name is iron(III) chloride

1

Calculation 0.224g O combines with 0.142g Cl 0.014 mol O combines with 0.004 mol Cl

1

3.5 mol O combines with 1 mol Cl

1

formula is Cl2O7

1

(d)(i)

Equation 2ClO2 —> Cl 2 + 2 O2

1

(ii)

name or formula, one of:

(c)(i)

chlorine, sulphur dioxide or sulphur trioxide

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