[Fzang]

I'm writing a paper on the bomb calorimetry I did last week, and I'm really really in trouble. Organic and inorganic chemistry, not a problem. Physical chemistry? Makes sense not. On top of that the manual for the experiment hardly explains anything.

So, it basically goes like this:

- Calculate internal energy from the number the machine gives you.
- Calculate internal energy for the amount of nitric acid produced (found by titration) in a specific way.
- Add these numbers up somehow to get the full internal energy of the compound.
- Calculate enthalpy of formation from the internal energy.

I've calculated the enthalpy of formation for a compound without nitrogen. This result is about 0.5% off known measured values (or w/e you call them. The "determined" numbers you find in the back of your book).

Now with the nitrogen correction I'm almost 11% off, so I must be doing something wrong. I have no idea what though, and I'd be so happy if you'd look through my calculations and see what I'm doing wrong.

http://cl.ly/6x3c

In my manual I also have the formula
d_rU_compound = d_rU_bomb + n_HNO3/2 * d_rU_HNO3

Where d_rU is supposed to mean "delta internal energy of reaction". I have no idea how to use it correctly though. If U is given in kJ/mol, and n is given in mol, then the units won't add up correctly, but instead give kJ/mol+kJ which makes little sense.