The Electrolysis of Solutions

In a mixture of ions it is the ion which is [blank_start]lower[blank_end] in the reactivity series that will be discharged and gain electrons (i.e. is [blank_start]reduced[blank_end])

So as [blank_start]hydrogen[blank_end] is lower than [blank_start]sodium[blank_end] in the reactivity series it is the [blank_start]H+[blank_end] ion which is discharged and so the element [blank_start]H2[blank_end] will be formed.

The half equation for this is: [blank_start]2H+[blank_end] + [blank_start]2e-[blank_end] = [blank_start]H2[blank_end]

At the anode [blank_start]oxygen[blank_end] is made unless a [blank_start]halide[blank_end] ion is present, in which case the [blank_start]halogen[blank_end] is made.

Write the half equation for the formation of oxygen (from hydroxide ions) at the anode: [blank_start]4OH-[blank_end] = [blank_start]O[blank_end]2 + 2[blank_start]H2O[blank_end] + [blank_start]4e[blank_end]-

What will be produced at the Cathode in the electrolysis of a potassium sulphate solution?

What will be produced at the anode in the electrolysis of a potassium sulphate solution?

What will be produced at the cathode in the electrolysis of a Magnesium Bromide solution?

What will be produced at the anode in the electrolysis of a Magnesium Bromide solution?