calculate the standard free energy change.?

Question

For the reaction whose reactants and products are:



reactants: SO2 (g) O2 (g)


products: SO3 (g)



calculate the standard free energy change (kJ/mole) from the standard free energies of formation.


The answer depends on how you balance the equation.
For this question balance the equation using the smallest ratio of WHOLE numbers.

i think the balanced equation with whole numbers would be

2 SO2 (g) O2 (g) == 2SO3 (g)

and i know to figure out the delta G i need to subract the the standard free energies of formation of reactants from products.

so it would be

(2 x [SO3]) - (2 x [SO2)

O2 is not ocunted cause it's 0 i think...

BUT! what is the the standard free energies of formation for SO3 and SO2. i kinda dont have my book with me.

I searched the web. but couldnt find it...

HELP PLEASE!!!

Answer 1

The values may be slightly different in different texts, but I've got these:

SO3: -370.4 kJ/mol
SO2: -300.4 kJ/mol