Please help with the following chemistry problems.
Find the standard electrode potential, E°, and DG° for the following reaction:
4HIO3(aq) --> I2(s) + 2H2O + 5O2(g)
Is the reaction spontaneous? Can iodic acid exist?
Hint: HIO3 is ionized in water.
4HIO3(aq) --> 2 I2(s) + 2H2O + 5O2(g)
First, we look up the half-reactions:
IO3- + 6H+ + 5e- --> 1/2 I2 + 3H2O E° = 1.195 V
O2 + 4H+ + 4e- --> 2 H2O E° = 1.229 V
Now, we must reverse the second equation and change the sign of E°.
2 H2O --> O2 + 4H+ + 4e- E° = -1.229 V
Next, we must make sure that the electrons balance. To do this, we must multiple the first equation by 4 and the second equation by 5. In total, there will be a redox reaction involving 20 electrons.
4 IO3- + 24 H+ + 20e- --> 2 I2 + 12 H2O E° = 1.195 V
10 H2O --> 5 O2 + 20H+ + 20e- ...
The following posting helps find the standard electrode potential, E°, and DG° for a reaction. Step by step calculations are given.