Best Method

[Tamera Scott 1G]

Lavelle mentioned in lecture that bond enthalpies were not very accurate when calculating reaction enthalpies. Out of the remaining 2 methods, which one gives you a more accurate number?

[AdityaGuru1H]

The other option would probably be using the standard enthalpy of formation method because the other method is only for combining the enthalpy of multiple reactions. On the test however the method that we use will probably be dertimned by what information we are given so i wouldn't worry too much about which is the most accurate and instead just understanding why all of them work

[Erin Kim 2G]

I would use Hess' Law if the total deltaH is given of the reaction to add the two reactions, but if the total change in heat is not given I would use the Hf tables to find the specific heats of each of the reactants and products and add those to get the total deltaH.

[George Ghaly 2L]

It all depends on the initial information given in the problem, there is no true best way to solve this questions but some options are better for certain types of questions.

[Megan_Ervin_1F]

DO we have to know how to use every single method? Or, can we just always default to the method we feel most comfortable with?

[Brian Kwak 1D]

Methods one and three are more accurate than method 2. The reason is because for the bond enthalpy chart, it has the average values of the bond enthalpies and doesn’t take into consideration the reaction. Methods 1 and 3 should yield similar results that are more accurate than method 2.
It really depends on the information the question gives you which will kinda dictate which method you will be using.
I think it would be wise to know all the methods because depending on the information the question gives you might have to use them all for an exam.

[Nandhini_2K]

I think it really depends on what is given in the problem already.

[Esther Lee 4H]

depends on the type of question. if youre not given too much information it might be easier to set up a table but if youre able to solve it through hess' method you can do it that way