[Akuma2636]

I was looking at the questions that we have to do, I read over the whole enthalpy section 3 times, and I still do understand it in relation to the question we were asked.
The question was:
Compare the enthalpies of the following:
a. A hydrogen molecule and two separate hydrogen atoms.
b. A hydrogen fluoride molecule and separate hydrogen and fluorine atoms

I just don't get it!!! Please help me!!!

[xiankai]

enthalpy is the change in energy level of the reactants in the specified reaction/process.

bond-breaking has a positive enthalpy as energy is taken in to break the bonds.
bond-making has a negative enthalpy as energy is released after making the bonds.

a. hydrogen molecule (H₂) vs. hydrogen atoms (H)

what is the difference between the two in terms of bonds?

b. hydrogen fluoride molecule (HF) vs. seperate hydrogen and fluorine atoms (H + F)

etc.

[Akuma2636]

a. hydrogen molecule (H2) vs. hydrogen atoms (H)

So for the first one would I say that H2 has a lower enthalpy than hydrogen atoms because non bonded atoms have a standard enthalpy whilst the hydrogen molecule has a lower enthalpy because it has already bonded and energy is released after bond forming.

Does that sound right?

[xiankai]

you got it.

[Akuma2636]

Thankies ^_^