Calculate the standard emf for the following reaction:

2ClO3 - (aq) + 10Br - (aq) + 12H + (aq) - - > Cl2 (g) + 5Br2 (l) + 6H2O (l)

In order to solve this, we need to know the standard cell potentials of the half reaction from the given overall reaction.

The half reactions with their standard cell potentials are:

2ClO-3 (aq) + 12H + (aq) + 10e - = Cl2 (g) + 6H2O (l)

E = + 1.47

Br (l) + 2e - = 2Br-

E = + 1.065

We solve for the standard emf by subtracting the standard emf of the oxidation from the reducation, so:

1.47 - 1.065 = 0.405 V