Enthalpy Calculations

We begin with a story. Once upon a time there was a mole. One day, the mole disappeared. About 2 and a half months later, it returned. The end.

DELTA H ----> CHANGE IN ENERGY (kJ/mol)

But what does that mean? How do I find delta H?
CALM DOWN IM GETTING THERE.

Here's an example equation:

Ba + O2 --->  BaO + 1092kJ
Find delta H for 1 mole of product

STEP NUMERO UNO:
Look at it. Is it balanced? Is it equal? If I put both sides on either side of a scale would it even out? Yes, because they both weigh almost nothing? THAT IS BESIDE THE POINT. The point is, NO IT IS NOT BALANCED.

2Ba + O2 --->  2BaO + 1092kJ

Now, that looks much better.

STEP NUMERO DOS:

Take one part of the product side of the equation. In this case, only 2 BaO will do. Now take the energy (1092kJ) and put it into the form of kJ/mol like so:

-1092kJ/2 mol BaO

You may simplify this output to
-546kJ/1 mol BaO

So we just find delta H for these equations? NO
YOU CAN FIND ALL KINDS OF THINGS WHATEVER YOUR HEART DESIRES
except not, mostly just chemistry stuff

eg. Using the same equation (because im cool like that) Find the number of grams of O2 needed to produce 900 kJ of energy.

2Ba + O2 --->  2BaO + 1092kJ

Start with the energy needed to be produced:

-900 kJ

Find and utilize the conversion factor to end up with moles

(-900kJ)(1 mol O2/-1092) = 0.824 mol O2
Convert moles to grams:
(0.824 mol O2)(32g/1 mol O2) = 26.4 g

Asian guy explains everything