IGCSE Chemistry 4335/2H Mark Scheme (Results) November 2008

[Pages:17]IGCSE Chemistry 4335/2H Mark Scheme (Results) November 2008

IGCSE

IGCSE Chemistry (4335/2H)

Edexcel Limited. Registered in England and Wales No. 4496750 Registered Office: One90 High Holborn, London WC1V 7BH

The following acronyms are used

owtte or words to that effect

ecf

error carried forward

dop

dependent on previous

nwn

no working necessary

4335_2H 0811

Question Number 1 (a) (i)

Question Number 1 (a) (ii)

Question Number 1 (b)

Question Number 1 (c)

Question Number 1 (d) (i)

Question Number 1 (d) (ii)

Question Number 1 (d) (iii)

Correct Answer

Notes

Mark

hydrogen peroxide water + oxygen (1)

Correct Answer

Notes

Mark

catalyst (1)

Correct Answer

Notes

Mark

over water / displacement of air with

Accept "through

downward delivery / upward displacement of water".

air. Could be shown on a diagram.

(1)

Correct Answer

Notes

Mark

relights a glowing splint

Reject "glows more

brightly"

(1)

Correct Answer

Notes

Mark

Red (ignore pale/dark), crimson / scarlet

Reject references to

orange / yellow /pink

(1)

Correct Answer

Notes

Mark

electron transfer

Covalent / sharing

1

from lithium to oxygen

scores zero

1

Li atoms each lose one electron and O atom

1

gains two electrons

(3)

Correct Answer

Li+ O2?

Notes

Both correct but reversed scores 1

Mark

1 1 (2)

(Total 10 marks)

4335_2H 0811

Question Number 2 (a)

Question Number 2 (b) (i)

Question Number 2 (b) (ii)

Question Number 2 (b) (iii)

Question Number 2 (c) (i)

Question Number 2 (c) (ii)

Question Number 2 (d) (i)

Question Number 2 (d) (ii)

Correct Answer

Notes

Mark

Brown / red brown (reject "light", accept Reject red alone or

1

"dark")

reference to orange

Grey (reject "light", accept "dark")/ black Reject purple or violet

1

(2)

Correct Answer

Notes

Mark

diffusion (1)

Correct Answer

Notes

Mark

Br2(l) Br2(g) Reactants = 1, products = 1

(2)

Correct Answer

Notes

Mark

moving (faster)

1

further apart owtte

1

(2)

Correct Answer

Notes

Mark

bromine + hydrogen hydrogen bromide Ignore "gas" (1)

Correct Answer

Notes

Mark

hydrobromic (acid) (1)

Correct Answer

Notes

Mark

melt/molten/fused (lead (II) bromide)

Allow "dissolve in

water"

not just heat or add

water

(1)

Correct Answer

Notes

Mark

(A) electrons (B) lead(II) ions / Pb2+ (C) bromide ions / Br?

1

If ions named in wrong

1

order, award 1 mark

1

for both. If "ions"

omitted twice, max 1

for B and C. If B and C

"positive ions" and

"negative ions" - 1

mark.

(3)

4335_2H 0811

Question Number 2 (e)

Correct Answer Gain of electrons (by Pb2+)

Notes

Mark

(1) (Total 14 marks)

4335_2H 0811

Question Number 3 (a) (i)

Question Number 3 (a) (ii)

Question Number 3 (b) (i)

Question Number 3 (b) (ii)

Question Number 3 (c)

Correct Answer

Notes

Mark

neutralisation

Accept "exothermic" (1)

Correct Answer

Notes

Mark

KOH + HNO3 KNO3 + H2O Reactants = 1, products = 1

Correct formulae with

incorrect balancing = 1

Ignore state symbols

(2)

Correct Answer

Notes

Mark

burette (1)

Correct Answer

Notes

Mark

pink / red (reject purple) colourless

Award 1 mark for

1

correct colours in

1

wrong order

One colour on its own

is zero

(2)

Correct Answer

Notes

Mark

Same volumes without indicator

1

Heat/warm/boil/leave(in a warm) to

1

evaporate water

Cool (not given if not heated)

1

filter off crystals

1

dry between filter paper/ in (warm) oven

1

(not leave to dry)

if no attempt at M2, max 1

if heat to dryness in M2, max 2

OR

Boil titration mixture with charcoal and filter Heat/warm/boil/leave(in a warm) to evaporate water Cool (not given if not heated) filter off crystals dry between filter paper/ in (warm) oven (not leave to dry) if no attempt at M2, max 1 if heat to dryness in M2, max 2

(5)

(Total 11 marks)

4335_2H 0811

Question Number 4 (a) (i)

Question Number 4 (a) (ii)

Question Number 4 (b)

Question Number 4 (c) (i)

Question Number 4 (c) (ii)

Correct Answer

C2H4 + H2O CH3CH2OH

Correct Answer (concentrated) phosphoric acid

Correct Answer sugar / sucrose / glucose yeast two from dissolve in water absence of air temperature in range 20 - 40 ?C Any two conditions for 1 mark each

Correct Answer

CH3CH2OH(l) + CH3COOH(l) CH3COOCH2CH3(l) + H2O(l) Reactants = 1, products = 1, state symbols (dependent on correct formulae) = 1

Correct Answer pleasant/fruity/glue smell / oily drops

Notes

Mark

Accept C2H5OH (1)

Notes

Mark

Reject "dilute" (1)

Notes

Mark

Additional wrong

1

reagents negate sugar

1

mark

2

Reject "heat" accept "warm"

(4)

Notes

Mark

Accept C2H5 in place of CH2CH3

(3)

Notes

Mark

Not just "smell" (1)

(Total 10 marks)

4335_2H 0811

Question Number 5 (a) (i)

Question Number 5 (a) (ii) Question Number 5 (b)

Question Number 5 (c) (i)

Question Number 5 (c) (ii)

Correct Answer

Notes

number of electrons in outer shell is same as group OR number of shells with electrons in is same as period

Mark (1)

Correct Answer

Notes

Mark

2.8.8.2

Accept any

punctuation

(1)

Correct Answer

Notes

Mark

ATOMS with (If atoms omitted, max 1)

same atomic number/same number of

Ignore same electrons

protons/same element(1)

different numbers of neutrons/mass number

(1)

(2)

Correct Answer

Notes Mark

Number of neutrons

12 (1)

Number of protons

12(1)

Atomic

Mass

number of number

isotope of isotope

12

24

Percentage isotope in the element

79

13

12

12

25(1)

10(1)

14

12

12(1)

26

11

(5)

Correct Answer Magnesium/Mg

Notes

Mark (1)

4335_2H 0811

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