Chemistry Reference
In-Depth Information
Electricity and chemistry
●
Additional questions
1
a simple explanation of the 'missing' gas in
B
.
What was the explanation? (Assume that the
apparatus was working perfectly).
e
Write down the equations which describe the
production of the gases at the electrodes in
A
and
B
.
f
(ii)
If the concentrated solution of potassium
chloride was now replaced by dilute sodium
hydroxide what gases would be produced at
A
and
B
?
(ii)
In what ratio would you expect these gases to
be produced?
3
Explain the meaning of each of the following
terms. Use a suitable example, in each case, to help
with your explanation.
a
Anode.
b
Cathode.
c
Electrolysis.
d
Electrolyte.
A
B
X
Y
dilute sulfuric acid
-
+
This is a diagram of an experiment in which
electricity was passed through a mixture of distilled
water containing a little dilute sulfuric acid.
a
Name the gas that collects at
A
.
b
Name the gas that collects at
B
.
c
If 100 cm
3
of gas collects in
A
how much would
there be in
B
?
d
Name the metal usually used for
X
and
Y
.
e
X
is called the ___________ .
f
Y
is called the ___________ .
g
Write down the formulae of the three ions
present in the solution.
h
Write down the equations for the reactions
that take place at both
X
and
Y
(or describe the
changes that take place if you cannot write the
equations).
2
The apparatus shown in the diagram below was
used to investigate the gases produced when a
concentrated solution of potassium chloride was
electrolysed.
e
Anion.
f
Cation.
g
Oxidation.
h
Reduction.
4
Copper is purified by electrolysis, as in the example
shown below.
A
B
C
D
A
B
a
Name the materials used for the electrodes
A
and
B
.
b
Name the electrolyte
C
and substance
D
.
c
Why is substance
D
of economic importance in
respect of this process?
d
Write equations for the reactions which take place
at the cathode and anode during this process.
e
Draw a labelled diagram to show the cell after
electrolysis has taken place.
f
Why has electrolyte
C
to be acidified with the
dilute sulfuric acid?
g
Why does copper have to be 99.99% pure for use
in electrical cables?
concentrated solution
of potassium chloride
+
-
a
Name a non-metal suitable for use as electrodes.
b
Name the gas collected in
A
and the gas
collected in
B
.
c
Describe how you would test the gases collected.
d
The volume of gas collected in
B
was slightly
less than that collected in
A
. The teacher said
the volumes should have been equal but gave
