What happens when voltage is increased during electrolysis?
The materials required for this science fair project:
- tap water
- 4 table spoons of salt
- 4 1.5V batteries
- a battery holder
- 2 jumper wire that have crocodile clips at both ends
- 2 test tubes
- 2 PVC insulated copper wires (5mm2) 150mm in length each
- a stop watch
- a pair of pliers
- a black color permanent marker pen
1. For this science fair project, the independent variables are the number of batteries used (ie: the DC voltage applied to the electrolyte). The dependent variable is the time taken to collect the released hydrogen gas. This is measured by using the stopwatch. The constants (control variables) are the amount of the salt content in the electrolyte solution, the amount of oxygen collected in the test tube and the surface area of exposed copper in the electrolyte solution.
2. Strip the insulation of both copper wires exposing approximately 30mm of wire on both ends, using the pliers. Bend the wires into ‘S’ shapes and place them inside the beaker as shown in figure 1 below.
3. Fill the beaker with water and add 1 tablespoon of salt. Dilute the salt in water.
4. Draw a line using the permanent marker pen along the circumference of the test tube. The line should be placed at about the center of the test tube. Fill the 2 test tubes with water and place them inverted, inside the beaker as shown in Figure1. The exposed copper wire should be placed entirely within the test tube.
5. The test is started by using one DC1.5V battery. The battery terminals are connected to the copper wire, using the jumper wires. Start the stopwatch. How long does it take for hydrogen to accumulate to the level of the line? Record this time in the table below. Procedures 3 to 5 are repeated using 2 batteries (DC3V), 3 batteries (DC4.5V) and 4 batteries (DC6V).
Use only batteries. Do not connect to mains supply. Conduct the experiment under supervision of a qualified person. Highly flammable gasses will be released. Ensure that protective gear is worn at all times.