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Whether the voltage affects the amount of gas produced during the electrolysis of sodium chloride solution.

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Electrolysis Coursework Aim An investigation into whether the voltage affects the amount of gas produced during the electrolysis of sodium chloride solution. Prediction When electrolysis of sodium chloride solution takes place there are four ions produced. These are Na+, H+, Cl-, OH-. The sodium and hydrogen are attracted to the cathode but it is the hydrogen given off because it is the less reactive of the two. The half equation for this is H+ +2e�H2. The chloride ion and hydroxide ion will be attracted to the anode because they are both negative but it is the chloride ion that will be given off because it is always the halogen that is given off. ...read more.


Diagram Method 1. Set up equipment as above. 2. Fill a measuring cylinder with water, and invert over the cathode. 3. Set the power pack at the voltage required. 4. Time for 30s and record results. As electrons flow to the cathode, positive ions are attracted to it. When Cl- ions reach the cathode it loses its electrons. This will give off Cl2 gas. As the gas is given off it will begin to fill the inverted measuring cylinder displacing the water. We can then measure the amount of gas that has been given off in a certain length of time according to how much water has been displaced. ...read more.


Really the experiment should be performed with a new electrode for every test to ensure that it is completely clean, but this would become costly. There is a possibility that the concentration of NaCl varied between readings, because we used water in the measuring cylinder to measure the amount of gas given off. As this was inserted into the Brine solution, the water would mix with the brine and alter the concentration. To prevent this, I should have put brine in the measuring cylinder. Another possible reason for the anomalous results could be that it is almost impossible to collect all the gas that is given off for every reading this may mean that I did not collect the entirely correct results for every voltage. ...read more.

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