Module 3 - Benjamin-Mills

SS3.2
Simple electrochemical
cells
This activity gives you a chance to set up a number of
electrochemical cells. You will need to use your
experimental skills to obtain reliable data on the
cells. You then have an opportunity to develop your
abilities in analysing data. You will learn about the
relationship between the potential differences of
different cells. Chemical Ideas 9.2 will help you
interpret your results.
Requirements
● leads with crocodile clips (2)
● 100 cm 3 beakers (3)
● iron nail
● copper metal strip (long enough to dip into the solution
in the beaker)
● zinc metal strip (long enough to dip into the solution in
the beaker)
● emery paper
● distilled water
● copper(II) sulphate solution, 1.00 mol dm –3 (50 cm 3 )
● iron(II) sulphate solution, 1.00 mol dm –3 (50 cm 3 )
● zinc(II) sulphate solution, 1.00 mol dm –3 (50 cm 3 )
● filter paper strips soaked in saturated potassium
nitrate(V) solution
● high-resistance voltmeter (e.g. pH/mV meter)
copper(II) sulphate
CARE Eye protection
must be worn.
HARMFUL
WEAR EYE
PROTECTION
Introduction
You have probably used batteries in a number of different appliances. They are
often called ‘dry’ cells because, for convenience, pastes rather than solutions are
used in making up the cells. They are all based on redox reactions arranged to
occur in two half-cells. The electricity produced is generated by a chemical
reaction taking place in the cell.
In this activity you will set up a number of metal ion/metal half-cells, combine
them into cells, and measure the potential differences with a high-resistance
voltmeter.
What you do
1 Clean the metal strips by rubbing them with emery paper, rinsing in distilled
water, and drying them.
2 Pour the copper(II) sulphate solution (CARE Harmful) into a beaker and
place the copper metal strip into it. This forms the copper half-cell (Figure
1). You can bend the foil over the edge of the beaker and hold it in place
with the crocodile clip.
copper
metal
copper(ll)
sulphate
solution
The beaker contains both
copper atoms (in the metal)
and copper ions (in the solution)
Figure 1 A copper half-cell, Cu 2+ (aq)/Cu(s)
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