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Entropy and enthalpy 
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#1
Nov1410, 02:23 PM

P: 76

1. The problem statement, all variables and given/known data
consider the decomposition of calcium carbonate: CaCO3(s) yields CaO(s) + CO2(g) a) calculate delta H and delta S from standard thermodynamic data. b) calculate delta G at 25.0C 2. Relevant equations G = H  TS 3. The attempt at a solution i added up all the thermodynamic data and got 2236 KJ/mol now this is the delta G but for (a) im not given a temperature(is it 25C) and i have to solve for two variables. not sure what to do. 


#2
Nov1410, 07:21 PM

P: 76

anybody please, can u at least get me started.



#3
Nov1610, 07:50 AM

P: 82

1. list Hf values for CaCO3, CaO, CO2 (1207,635,394 kJ/mole) (this is at 25C, 1 atm)
2. H(reaction)=SUM(r*Hf), where r= reactioncoefficient= negative for reactants) 3. similar for entropy. 4. use G=HTS for the calculation of G(reaction) 


#4
Nov1610, 08:52 PM

P: 54

Entropy and enthalpy
Delta H and Delta S Values:
http://chemtables.tk/ (click Entropy and Enthalpy Tab) Use Products  Reactants with the values on the website above to determine the overall delta H and delta S. (Values for Products)  (Values for Reactants) Then, once you have delta S and delta H, you can use the formula you provided above to find delta G. You can also verify that your delta G is correct by using the values in the chart to see if you come out with the same answer. Make sure that you keep your values consistent! Entropy is often in J/mol while the others are in kJ/mol. 


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