Question

A chemistry teacher wants to prepare Br2. The teacher has access to the following three reagents: NaBr(aq), Cl2(g), and I2(s).


Half-Reaction E° at 25°C(V)

Br2+2e−→2Br− 1.07

Cl2+2e−→2Cl− 1.36

I2+2e−→2I− 0.53

(b) Using the data in the table above, write the balanced equation for the thermodynamically favorable reaction that will produce Br2 when the teacher combines two of the reagents. Justify that the reaction is thermodynamically favorable by calculating the value of E° for the reaction.

Answer 1

2NaBr + Cl2 = 2NaCl + Br2

2NaBr + I2 = 2NaI + Br2

The first step is to determine the cell potential at its standard state — concentrations of 1 mol/L and pressures of 1 atm at 25°C. Then you need to use Nernst equation.