Electrolysis Investigation

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Electrolysis Investigation Planning In this investigation, I will assess how changing the electric current in the electrolysis of acidified water affects the rate at which hydrogen gas is produced. The solution to be electrolysed is made up using acid and water. It is of little consequence what acid is used however in this case I will use Sulphuric acid (H2SO4). When H2SO4 is put in water it is dissociated and forms ions: H2SO4 → 2H (2+) + SO4 (2-) Ions are also present from the water in the solution: H2O → H (+) + OH (-) During the electrolysis process, the positive hydrogen ions move towards the cathode and the negative hydroxide and sulphate ions move towards the anode. At the cathode the hydrogen ions gain an electron. They are discharged and are converted into hydrogen gas: 2H (+) + 2e (-) → H2 At the anode, the hydroxide, not the sulphate ions are discharged. Water and oxygen gas are formed: 4OH (-) → 2 H2O + O2 + 4e (-) The hydrogen gas can be collected and measured. The greater the volume of hydrogen gas formed over a set period of time, the faster electrolysis is occurring. In the experiment there are several possible ways of changing the electric current such as changing the voltage or the position of the electrodes within the electrolysis cell. However, it was found from preliminary work that the most effective way to change the current was to change the concentration of the acid solution. The preliminary work showed that the greater the concentration of the acid, the greater the current. Ohm's law states that R(resistance) = V(voltage) I (current) Therefore, I = V R Therefore, if V is constant, in order to increase I, R must decrease. Inversely, to decrease I, R must increase. The value of R depends on how easy it is for the electric charge to pass through the conductor. Therefore to decrease R, the passage must be made easier and to

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