Hey everyone,
i'm trying to get my head around Enthalpy change, and the calculations. Okay, let's say we're working out the Enthalpy change using Hess' law cycles - I think this is determining enthalpy change indirectly. This is where I get confused! I have an idea of what to do, I just don't understand why it is that I do it - if you get what I mean.
I wanted to know
1) - how to calculate ΔH combustion using cycle (if possible)
2)- how to calculate ΔH of reaction, using Enthalpy change of combustion values
3)- Why do the arrows point towards the combustion products when calculating ΔH of formation, using combustion values (using Hess' law cycle)
4)- Why do the arrows point from the elements to the reactants when calculating ΔH of reaction, using formation values (using Hess' law cycle)
I think all of my questions are in terms of standard enthalpy change.
Any help would be great, thanks! I'm an A2 Chemistry student, and I got bored, so I thought I'd revisit some AS stuff that I never really understood!