1.55 write ionic half-equations representing the reactions at the electrodes during electrolysis

IONIC HALF-EQUATIONS:

- At the positive electrode, also known as the anode, electrons are lost.
2Br- -> Br2 + 2e-

- At the negative electrode, also known as the cathode, electrons are gained.
Pb^2+ + 2e- -> Pb

As http://hannahhelpchemistry.blogspot.co.uk/ has said:
- At the anode the half-equation should be equal on both sides: 1- -> 1-.
- At the cathode the half-equation should be equal on both sides: 0 -> 0.