Topscore Gchem

[alanan84]

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The question gives you the standard enthalpy of formation for NO which is 90.25KJ/mole as well as a table of Absolute entropies:

N2 = 192
NO = 211
O2 = 205

The rxn is N2(g) + O2(g) -> 2NO(g) and you're asked to get delta G at 25C.

So I understand you find delta S using the given values and you multiple the enthalpy of formation for NO by 2 b/c there's 2 moles and then you plug it in to the Gibbs free energy equation but this is the answer they give:

delta G = 180.5 - (273+25)(25)(1x10^-3)

Where does the 1x10^-3 come from?

 

[milowenwen]

the units of entropies is J, not KJ; however, the units of enthapy formation is KJ. so you need to convert J to KJ by * 10-3.

 

[alanan84]

Thanks!