Investigation to see how the voltage changes when we change the metals used in a cell

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Investigation to see how the voltage changes when we change the metals used in a cell

Method

During this investigation I performed two different experiments. Both experiments were to see how the voltage changed when using two different metals as electrolytes in a battery. When using sulphuric acid as the electrolyte I set up the experiment as shown in the diagram. The other experiment used a grapefruit (therefore citric acid) as the electrolyte. We set it up in the same way as we set up the experiment when using sulphuric acid, except we inserted the pieces of metal (the electrodes) into the grapefruit. The wires were attached to the pieces of metal using crocodile clips. We then held the metals in the electrolyte until the voltage reading on the voltmeter remained steady.

I repeated the results once when using sulphuric acid, but did not have enough time to repeat the results when using citric acid.

Results

Sulphuric acid-1st set of results

Metal 1

Mg

Al

Zn

Sn

Pb

Cu

Metal 2

Mg

-------

Al

0.550

--------

Zn

0.130

0.330

---------

Sn

0.680

0.170

0.380

--------

Pb

0.870

0.170

0.640

0.240

--------

Cu

.050

0.410

0.830

0.720

0.410

--------

Sulphuric acid-2nd set of results

Metal 1

Mg

Al

Zn

Sn

Pb

Cu

Metal 2

Mg

-------

Al

x

--------

Zn

x

0.610

---------

Sn

.470

0.030

x

--------

Pb

0.720

0.230

x

0.050

--------

Cu

0.710

0.750

0.960

0.350

0.420

--------

Averages for sulphuric acid including anomalous results

st results with H2SO4 (Volts)

Metal 1

Mg

Al

Zn

Sn

Pb

Cu

2nd results with H2SO4 (Volts)

Metal 2

Mg

-------

x

x

x

x

x

Al

0.550

--------

x

x

x

x

Zn

0.130

0.470

---------

x

x

x

Sn

.075

0.100

0.380

--------

x

x

Pb

0.795

0.200

0.640

0.145

--------

x

Cu

0.880

0.580

0.895

0.535

0.415

--------

Grapefruit

Results using Grapefruit

Metal 1

Mg

Al

Zn

Sn

Pb

Cu

Metal 2

Mg

-------

x

x

x

x

x

Al

0.630

-------

x

x

x

x

Zn

0.200

0.560

-------

x

x

x

Sn

0.590

0.100

0.370

-------

x

x

Pb

.250

0.040

0.560

0.110

-------

x

Cu

.190

0.460

0.970

0.560

0.400

-------

Analysis

I have highlighted the anomalous results in red above. When using the sulphuric acid as the electrolyte, I repeated the experiment once. I have drawn charts that show the results from the experiments. I drew the charts by drawing a horizontal line across the page representing Magnesium's voltage as 0. Over this line I have drawn 6 vertical lines representing each of the metals I used. The further the points are from the horizontal line represents the larger the voltage produced.
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When looking at the charts, except for a couple of the anomalous results that have been circled, it is easy to see that metals of the same type are on a very similar horizontal line. The different coloured lines I have drawn, represent the lines of best fit for the averages of each of the different metals. I have not drawn a line of best fit for Aluminium because the points for Aluminium on each of the lines vary over a very large range, and so it would not be accurate. I have also drawn a chart which ...

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