How Can the Amount of Copper Extracted by Electrolysis Be Changed?

How can the amount of Copper extracted by electrolysis be changed?

Planning

We can change the amount of copper extracted by electrolysis by changing the time it is electrolysed. The copper ions from the positive electrode, are attracted to the negative electrode, because copper ions are positively charged, the copper sulphate solution allows copper ions to move to the negative electrode. When the copper leaves the impure copper electrode, it will leave the impurities at the bottom of the beaker.

The apparatus I will be using is:

A beaker

Copper Sulphate Solution

Electrodes

A voltmeter

Power Pack

Crocodile Clips

Wires

The variables I could change are the length of time, the amount of copper electrode dipped in the copper sulphate solution, the voltage or the concentration of the copper sulphate solution. The variable I will investigate is changing the time.

I have decided to measure the time in 1, 2, 4, 6, 8, 10, 12 minutes. I will repeat each experiment twice and if I have time three times, except the 1 minute, which is a preliminary result, and I will only do it once. I have chosen to do two minutes intervals in the time because my preliminary research of trying one minute showed that this was too small a time scale to show significant results.

I predict that the amount of copper ions that leaves the anode will increase and the size of the electrode will decrease, while the cathode will gain copper ions and increase in size as the time the experiment is left running increases.

The copper ions move through the copper sulphate to the negative electrode, because they are drawn to it, due to the copper ions being positively charged. This means the longer the experiment is left running, the more copper ions will be able to travel to the opposite electrode, causing the negative electrode to increase in size and the positive electrode to decrease in size.

I will keep my experiments fair by:

o Keeping the amount of copper sulphate solution at 50cm3.

o Starting the voltage at 4 volts.

o Keeping the widths of the electrodes the same

o Keeping the amount of each electrode in the copper sulphate solution equal

o Keeping the concentration of the copper sulphate solution the same

I will make sure that my experiments are accurate by:

o Not shaking the table

o Stopping the experiment at exactly the right point so that no extra or less copper collects.

Obtaining Evidence

Voltage: 4

Volume: 50cm3

Experiment 1

Time (mins) Added copper weight (g) Added copper weight (g)

Anode (+) Cathode (-)

1 0.95g „Ñ- 0.94g 0.90g „Ñ- 0.91g

2 0.94g „Ñ- 0.94g 0.91g „Ñ- 0.91g

4 0.94g „Ñ- 0.93g 0.91g „Ñ- 0.92g

6 0.93g „Ñ- 0.91g 0.92g „Ñ- 0.95g

8 0.91g „Ñ- 0.90g 0.95g „Ñ- 0.98g

10 1.32g „Ñ- 1.29g 1.93g „Ñ- 1.98g

12 1.29g „Ñ- 1.22g 1.98g „Ñ- 2.04g

Voltage: 4

Volume: 50cm3

Experiment 2

Time (mins) Added copper weight (g) Added copper weight (g)

Anode (+) Cathode (-)

2 1.46g „Ñ- 1.45g 1.72g „Ñ- 1.75g

4 1.45g „Ñ- 1.39g 1.75g „Ñ- 1.79g

6 1.39g „Ñ- 1.32g 1.79g „Ñ- 1.88g

8 1.27g „Ñ- 1.24g 1.90g „Ñ- 1.98g

10 1.53g „Ñ- 1.46g 1.66g „Ñ- 1.72g

12 1.22g „Ñ- 1.15g 2.04g „Ñ- 2.13g

Voltage: 4

Volume: 50cm3

Experiment 3

Time (mins) Added copper weight (g) Added copper weight (g)

Anode (+) Cathode (-)

2 1.32g „Ñ-