My aim of this experiment is to find out if the number of coulombs affects the amount of copper produced.

PREDICTION:

I predict that the more coulombs there are, the more copper there will be deposited on the cathode, and at the anode there will be oxygen given off. The predicted graph will look something like this:

SAFETY;

VARIABLES:

In this experiment I am going to vary the time we keep the experiment going as the longer we keep the experiment going the higher the number of coulombs there will be. I am going to change the amount of coulombs used in the experiment by keeping each part of the experiment going for longer.

TO MAKE THIS EXPERIMENT A FAIR TEST:

To make this experiment a fair test I am going to weigh the copper electrodes each time I sand it and I will use the same electrodes throughout the experiment. I am going to use the same voltage and amps in the whole experiment. We will also use 1 mole copper sulphate through the experiment.

 APPARATUS:

1 X beaker

1 X power pack

1 X stopwatch

4 X wires

1 X electrode holder

250ml copper sulphate solution

2 X copper electrodes

1 X ammeter

1 X variable resistor

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DIAGRAM:

MEASUREMENTS:

RANGES:

The ranges we are going to use for the time are going to have a difference of two minutes each time. We have chosen to do it in two minutes difference because in the preliminary experiment we found that doing the experiment with 5 minutes difference was too long so we chose two minutes difference. We have not started the experiment at zero because we know there will be no effect so it is pointless to do so.

HOW WE ARE DOING THE EXPERIMENT:

We are doing the experiment by varying the time because we know that the time varies the amount of coulombs there are; and the amount of coulombs there are effects the amount of copper deposited at the cathode. I know that the copper will be deposited at the cathode because the positive copper ions get attracted to the negative cathode, and that there will be oxygen give off at the positive anode because only halogens and oxygen can be given off there. The copper anode will decompose a bit because it breaks down in to the solution to bond with the sulphate. Therefore the cathode will gain weight and the anode will loose weight.

If our experiment is successful I expect my graph to look like this:

A diagram of the circuit will look like this:

Here the electron flow is kept going through the circuit for every two electrons taken from the cathode a copper ion, two electrons are set free at the anode by two oxygen ions. Technically the electrons freed at the anode flow through the circuit to the cathode, because metal ions are ALWAYS positive they move to the negative cathode and get deposited. Non-metal ions are ALWAYS negative (except for hydrogen) therefore moves to the positive anode and gets discharged. The copper is collected at the cathode:

          2+         -

2Cu  + 4e                Cu

and Oxygen is released at the anode because sulphate cannot be deposited and it is not a halogen:

                      2-       -

                2O – 4e               O2

The anode will decompose slightly so the mass lost, will be slightly higher than the mass gained on the cathode.

BIBLIOGRAPHY