When to use which method for calculating reaction enthalpies

[904936893]

How do you know which of the three methods to use when given a specific problem? Like when would you use Hess's Law vs. Bond Enthalpies vs. Standard Enthalpies of formation?

[405161024]

I think it depends on what values are given in the problem. But also I think Hess's law is more accurate than bond and standard enthalpies so if you can do either I would do Hess's

[Christina Chang 1C]

Do you know which equation to use for question 8.9 in the 6th edition textbook? I'm not sure which equation uses those variables.

[Tatum Keichline 2B]

for 8.9, use 8.206e-2Latm/kmol and 8.314J/kmol then convert to kJ and subtract that answer from kJ given.

[Elias Omar 1G]

Bond Enthalpies: Generally you do not want to use this method as it is unreliable. I'm actually not totally sure when you'd use this method.

Hess's Law: Remember Hess's Law is about adding enthalpies. You'll use this in problems involving the enthalpies of multiple reactions.

Standard Enthalpies: You'll need to use this method in pretty much any problem involving enthalpies at some point, as standard enthalpies are a part of calculating the overall enthalpies in a reaction, since each substance in a particular state has one.