What is the free energy change in kJ for the reaction below?
2 BrO3-(aq) + 12 H+(aq) + 5 Fe(s) « Br2(l) + 6 H2O(l) + 5 Fe2+(aq) E° = 1.960 V.
To determine the free energy change (ΔG) for the given reaction, you can use the equation:
ΔG = -nFE
where:
ΔG = Free energy change in joules (J)
n = Number of moles of electrons transferred in the balanced equation
F = Faraday's constant (96,485 C/mol of electrons)
E = Standard cell potential in volts (V)
Given that the standard cell potential (E°) is 1.960 V, we can calculate ΔG using the equation above.
First, we need to determine the number of moles of electrons transferred (n) by looking at the balanced equation. In this case, each mole of BrO3- requires 6 moles of electrons, so n = 2 moles of BrO3- x 6 moles of electrons = 12 moles of electrons.
Next, we substitute the values into the equation:
ΔG = -nFE
ΔG = -(12 mol)(96,485 C/mol)(1.960 V)
To convert the units from Coulombs (C) to joules (J), we multiply by the conversion factor 1 J = 1 C·V:
ΔG = -(12 mol)(96,485 C/mol)(1.960 J/C)
Finally, we can convert the result to kilojoules (kJ) by dividing by 1000:
ΔG = -(12 mol)(96,485 C/mol)(1.960 J/C) / 1000
Calculating this expression will give you the value of the free energy change (ΔG) in kilojoules (kJ).