An investigation into whether the voltage affects the amount of gas produced during the electrolysis of sodium chloride solution

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An investigation into whether the voltage affects the amount of gas produced during the electrolysis of sodium chloride solution.

Prediction:

I think that hydrogen gas will be produced due to the half equation

2H +2e àH this will be produced at the cathode because opposites attract and the hydrogen ions are positive. At the anode I think that chlorine will be produced due to the half equation 2CL -2e àCL the chlorine ions are negative so they are attracted to the positive electrode. I also think that as the voltage is increased the amount of hydrogen gas produced will increase this is because of a series of scientific equations: if the voltage is increased the current then is increased, this is because of ohms law, V=IxR, where the voltage is proportional to the current, if the current is increased the charge then increases because Q=IxT. The number of moles of electrons=charge
-:- 96500, this is Faradays constant from his 2nd law. The relationship between the amount of substance deposited at an electrode and the number of electrons that are passed around a circuit (current) can be used to calculate the expected volume of substance produced at the electrode. To find the amount of hydrogen gas produced at the electrode we would multiply the number of moles of hydrogen gas by 24, this is the area that one mole of any gas will occupy. Then I will have to multiply by 1000 to get the amount of hydrogen in cm³.

GRAPH

Too big to measure

I am going to use voltages 5,6,7,8,9 and10 because for voltages lower than five there was not a lot of gas produced this made it extremely difficult to measure the amount of gas. For voltages over 10 there was too much gas produced and it went out of both sized measuring tubes. I decided to do it for 2 minutes as this figure seemed to be the one where the results were at their best, they were easily measurable unlike the results for one and three minutes.

Method

Equipment list Diagram:

· Lab pack
· Brine
· Electrolysis cell
· 25ml measuring cylinder
· 10ml measuring cylinder
· Clamp stand
· Boss
· Clamp
· 2 plug to crock wires
· 1plug to plug wire
· Ammeter
· Sand paper
· Stop watch

Instructions

· Set up the equipment as shown in the diagram.

· Make sure the negative terminal on the lab pack is connected to the