A2 coursework help - electrolysis of dilute sodium chloride solution Watch

cleverbong
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I am currently doing an experiment on how the current would affect the number of moles of gases produced at the electrode using 0.1 mol dm-3 sodium chloride solution.
As it is dilute solution, oxygen gas should be discharged at the anode (-ve electrode) and hydrogen should be discharge at the cathode (+ve electrode).

However, although I can see gas bubbles rising from the two electrodes, I find that the reading at the anode side is the same (stays at 0.0 cm3) for a few minutes whereas the reading at the cathode side is increasing a lot.

1. Does anyone know why?

2. Even very dilute sodium chrloide solution, is chlorine still discharged first before oxygen discharges at the anode?

3. Will oxygen be given off at the anode eventually?

Any help would be appericated!!
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charco
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(Original post by cleverbong)
I am currently doing an experiment on how the current would affect the number of moles of gases produced at the electrode using 0.1 mol dm-3 sodium chloride solution.
As it is dilute solution, oxygen gas should be discharged at the anode (-ve electrode) and hydrogen should be discharge at the cathode (+ve electrode).

However, although I can see gas bubbles rising from the two electrodes, I find that the reading at the anode side is the same (stays at 0.0 cm3) for a few minutes whereas the reading at the cathode side is increasing a lot.

1. Does anyone know why?

2. Even very dilute sodium chrloide solution, is chlorine still discharged first before oxygen discharges at the anode?

Any help would be appericated!!
Very dilute would be below 0.001 M
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charco
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(Original post by cleverbong)
Anyone have other suggestions?
If you compare the relative concentrations of hydroxide ions (about 1 x 10-7) and chloride ions you should see that the much higher concentration of chloride ions leads to its oxidation at the anode. It is only when the chloride ion concentration falls to very low values that the hydroxide ions can complete.
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