[illuminatus104]

I'm trying to figure out the standard enthalpy of formation of acetone. I put it into its formation equation, which is 3 C + 3 H₃ + O ---> CH₃COCH₃. Now I don't know what to do. I'll keep cracking away - hopefully I have an answer before someone posts!


What if I write out the combustion reaction, add the standard enthalpies of CO₂ and H₂O and subtract those from the reactants acetone + O₂? I'd have to solve for acetone, in which case I get -2037.9 kj/mol

Hm, I think the answer is −249.4 kJ/mol, based on the datapage for acetone on wiki. I'll try to get that

[sjb]

I'm trying to figure out the standard enthalpy of formation of acetone. I put it into its formation equation, which is 3 C + 3 H₃ + O ---> CH₃COCH₃. Now I don't know what to do. I'll keep cracking away - hopefully I have an answer before someone posts!


What if I write out the combustion reaction, add the standard enthalpies of CO₂ and H₂O and subtract those from the reactants acetone + O₂? I'd have to solve for acetone, in which case I get -2037.9 kj/mol

Hm, I think the answer is −249.4 kJ/mol, based on the datapage for acetone on wiki. I'll try to get that

Try a balanced formation equation?

[magician4]

to calculate enthalpies ab initio is  a difficult task, and requires intense use of quantummechanical approaches.

Hence, almost all enthalpy data you'll find for whatsoever substances are measured, either directly or indirectly.

To measure the enthalpy of formation for acetone directly, i.e. to observe the process

6 C + 6 H₂ + O₂  2 CH₃COCH₃

to he best of my knowledge is impossible, as this won't happen (i.e. is a purely theoretical process)

However, you might calculate the enthalpy of formation for acetone indirectly - if you knew the enthalpy of combustion for acetone , for example, and made use of Hess's law


regards

Ingo