Accuracy of methods for finding enthalpy.

[Sophia Schiro]

Does anyone know how accurate each of the three methods for calculating the enthalpy of a reaction are? And how do we know which method to use?

[Katie Shi 1F]

Using bond enthalpies is the least accurate method as these are found using averages of different molecules. Using Hess's Law and standard reaction enthalpies is more accurate as these values are more individualized. We should know what method to use just based on what information is given to us in the problem.

[Tala Ayoub 1H]

I believe that using bond enthalpies is the least accurate method as mentioned by Professor in class today, and I'd assume that both using Hess's method and the enthalpy change of formation would be equally accurate although I'm not entirely sure. Additionally, I'd assume that we could use either one unless specified in the question as they'd all give the same result, personally, I wouldn't use the bond enthalpy method because as mentioned by Dr. Lavelle it is the least accurate.