Investigation into the factors affecting the current through an electrolysis cell

Having looked at methods of mineral extraction we saw that one method involves electrolysis. To control the products of electrolysis we may need to control the speed of the reaction. A measure of this is the current of flow of electricity.

Preliminary Work:

We conducted preliminary tests in order to become familiar to the method we were to use in the final experiment. The results we gathered gave us an idea on the results and their range to enable us to draw appropriate graphs with correct scales. Equipment was chosen and we were to use the same in our main tests. So the preliminary tests would give us time to figure how to work them. This is done so the main experiment could be set up and completed successfully.

Possible Variables:

From the preliminary tests and results we found a number of possible variables we could have used to investigate the factors affecting the current through an electrolysis cell. These are:

• The applied voltage
• Concentration
• Amount
• Type of electrode
• Size of electrode
• Distance between electrodes

Fig.1 shows that there are a greater amount of electrons at the anode and cathode when the voltage is higher. The greater amount of electrons, the greater amount of current.

Method:

Apparatus:

• Electrolysis cell
• Power pack (max: 12v)
• Voltmeter
• Ammeter
• Clamp Stands
• Leads

Diagram:

• Set up apparatus as above, making sure that the voltmeter is connected in parallel, and the ammeter in series

• Fill electrolysis cell with 100ml of potassium nitrate

• Set power pack to certain voltage

• Turn power on for short amount of time and note the real voltage and current

• For better results, replace potassium nitrate solution after every reading

• Do this for each voltage listed in the variables section

• Repeat three times and take averages for best results

Fig.2 shows what I predicted in my prediction. When the voltage is low, the current is low, when the voltage is high; the current is proportionally high, taking into account the resistance.

Evaluation:

The experiment was conducted well and fairly. All measurements were taken accurately using a syringe or measuring cylinder.

Although the results were reasonably accurate, and they supported what I said in my prediction, there was one slight anomaly. As you can see in my graph, the current apparently starts to rise at around 2.40/2.5V. This is not correct because voltage and current are proportional, and this means that they should both start at 0 in a graph. The most probable reason for this mishap is the accuracy of the ammeter, the readings were probably two small for it to read, or they were jumping around a lot, and this results in incorrect readings.

If I were to repeat this experiment, I would obtain a more accurate ammeter, and also use a rheostat, so I can achieve rounded voltages, that are the same for every repeat. This would make the experiment fairer, and the results more accurate.