Question

Use tabulated thermodynamic data to calculate ΔS° for the reaction:
C2H5OH(l) + 3O2(g) → 2CO2(g) + 3H2O(g)

Answer 1

ΔS° is the change in entropy of the reaction.
Entropy is a measure of how predictable the atoms behave, how disordered the path they take will be.
To calculate the change in entropy in a system... you're going subtract the change in entropy of the reactants (with respect to the molar ratio) from the change in entropy of the reactants (multiplying by the amount of moles in the balanced equation.

You need to look up the entropy values of your equation. --> here is a good site.
http://chemistry-reference.com/standard%20thermodynamic%20values.pdf

Answer 2

C2H5OH(l) + 3O2(g) → 2CO2(g) + 3H2O(g)

remember.. the higher the entropy the greater the disorder in the system.
C2H5OH(l) - ethanol S = 161.04 -->
3O2(g) - oxygen S = 205.3
2CO2(g) - carbon dioxide S =213.68
3H2O(g) - water vapor S = 188.72

So.. the change in entropy of the system is:(plugging in values of entropy)
2(213.68) + 3(188.72) - (161.4) + 3(205.3)= 1448.02

When the entropy of the system is greater than zero, than the system becomes more disordered through the course of the reaction.