Experimental chemistry - Chemistry - page 280

f It can form an ion of the type X − .
g One of its oxides is the catalyst in the Contact
Process.

17 The following techniques are used to separate
mixtures.

A simple distillation

[Total: 7]
(Cambridge IGCSE Chemistry 0620 Paper 31
Q1 June 2008)

B fractional distillation

C evaporation

15 a Complete the table which gives the names,
symbols, relative masses and relative charges of
the three subatomic particles.

D chromatography

Name Symbol Relative mass Relative charge

E filtration

e −

electron

F diffusion

proton 1

n 0

From this list, choose the most suitable technique
to separate the following.
a methane from a mixture of the gases, methane
and ethane

[3]
b Use the information in the table to explain the
following.
(ii) Atoms contain charged particles but they
are electrically neutral because they have no
overall charge.

[1]

b water from aqueous magnesium sulfate [1]

c glycine from a mixture of the amino acids,
glycine and lysine [2] [1]

(ii) Atoms can form positive ions. [2] d iron filings from a mixture of iron filings

and water (iii) Atoms of the same element can have

different masses.

[1]

[2] e zinc sulfate crystals from aqueous zinc

sulfate (iv) Scientists are certain that there are no

undiscovered elements missing from
the Periodic Table from hydrogen to
lawrencium. [1]
[Total: 10]
(Cambridge IGCSE Chemistry 0620 Paper 31
Q2 June 2008)

[1]

f hexane from a mixture of the liquids,
hexane and octane [1]
[Total: 6]
(Cambridge IGCSE Chemistry 0620 Paper 31
Q1 June 2011)

18 The apparatus shown below can be used to
measure the energy released when a liquid fuel
is burnt. The amount of energy released is
calculated from the increase in temperature of a
known amount of water.

16 Copper is purified by electrolysis.
a Complete the following.
The positive electrode (anode) is made from
______
The negative electrode (cathode) is made from
______
The electrolyte is aqueous ______ [3]
b Write an ionic equation for the reaction at the
positive electrode (anode).

iron can

[2]

c (i) Give two reasons why copper is used
in electric wiring, [2]
in cooking utensils. [2]
(ii) Give another use of copper. [1]
[Total: 10]
(Cambridge IGCSE Chemistry 0620 Paper 31
Q3 June 2008)

water

ethanol