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    Solving for Delta G

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    Can you explain what we are doing mathematically, canceling, multiplying etc.? Thank-you.

    I am trying to understand how to balance this equation.
    We were given the following data to solve for delta G (standard).

    S(s) + 3/2 O2(g)--------->SO3(g) delta G standard = -371kJ
    2SO2(g)+ O2(g)--------->2SO3(g) delta G standard = -142kJ

    Now calculate delta G standard for the reaction.

    delta G standard = delta H standard - T delta S standard

    Please explain in detail how to balance these two equations together and add. I do not understand where they are getting the 1/2 142 kJ0, and why on the second number we have no coefficient on -371 kJ then we end up with 71kJ - 371 kJ = -300? Could you please explain? Thank-you very much.
    Can you explain what they are doing with the 1/2 mathematically? I see now that we are getting rid of the SO3, however how are we doing it? Are we canceling it out?

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    Solution Preview

    S(s) + 3/2 O2(g)--------->SO3(g) -371kJ
    2SO2(g)+ O2(g)--------->2SO3(g) -142kJ

    We need to switch around the second equation so that the SO3 cancels. When we do, we must reverse the sign of the deltaG.

    Therefore, we write the following:

    S(s) + 3/2 O2(g) --------->SO3(g) ...

    Solution Summary

    The solution provided goes through the steps and explains what each does and why.