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Page 1

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How Science Works


Suggest two reasons why all of the points do not lie on the line of best fit.

any two sensible errors eg
timing errors and / or example
measurement errors and / or
example
apparatus errors and / or example
human / experimental / random
error and…

Page 2

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any two sensible suggestions eg:
weighing error
(copper) lost during washing
owtte
(copper) lost during electrolysis /
reaction owtte
electrodes not completely dry
impurities in the electrode
copper falling off when
removing electrode / copper from
cell



Explain why sun creams containing nanoparticles should…

Page 3

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Percentage yield

Method 2 has the higher atom economy.y.

any two sensible ideas from eg:
no / less waste
less materials / reactants needed /
used
fewer / no environmental
problems or less / no pollution
better for sustainable
development / resources running
out
more useful use of atoms
less…

Page 4

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so results will not be fair / valid /
reliable
companies would not give false
information because of damage to
reputation or it might lead to
litigation




Nanoparticles

Suggest and explain why the hip replacement made of nanocrystalline metal should last
longer than one made of normal metals.



harder
plus…

Page 5

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Electrolysis:?

electric current / electricity
plus one from:
is passed through ionic compound /
substance / electrolyte
passed through molten/aqueous
compound / substance
causing decomposition

Describe and explain how electrolysis is used to make pure copper from a lump of
impure copper.
any four from:
impure copper is anode /…

Page 6

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Covalent

Suggest and explain why silica is used to make bricks for hightemperature furnaces.
In your answer, you should refer to the structure of, and bonding in, silica.4 marks



any four points from:
high melting point owtte
many or all atoms joined together
each silicon (atom) joined to four
oxygen…

Page 7

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poor conductor of heat

The carbon contacts are made of graphite. Springs push the contacts against the copper ring.
The contacts conduct electricity to the copper ring. The copper ring rotates rapidly but does
not stick or become worn because the graphite is soft and slippery.
Graphite has properties which…

Page 8

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a lot of energy needed to break
bonds
all atoms are joined by (covalent)
bonds
a large number of bonds would
need to be broken

Metals

Explain how metals conduct electricity



any two from:
outer shell electrons / electrons in
highest energy level (in metals)
electrons are delocalised / sea…

Page 9

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Rates of Reaction

Copper oxide reacts much faster with acid at 40 ºC than at 20 ºC.
Explain why in terms of particles.
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(2 marks)



any two from:
particles gain energy or particles
have more energy
particles move faster
collide more often
collide more energetically
more…

Page 10

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Acids

Copper sulfate (CuSO4) is a salt that has many uses.
An aqueous solution of copper sulfate can be made by reacting copper oxide (CuO) with an
acid.
3 (a) (i) Name this acid. .........................................................................................................
(1 mark)
3 (a) (ii) Write a balanced symbol equation, including state symbols, for this…

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