enthalpyhess

The Lyrics to Tessa's Enthalpy Song:

(eventually to be accompanied by a recording of her bad ukuleling)

Don't think you can make something with nothing on hand Elements couldn't be elephants without energy inputted You need heat- enthaply- to make nuclei bind Wih enthalpy of formation, the elephant's fine

CHORUS & do you eat, eat energy? you're endothermic do you release energy? you're exothermic the number of steps from place to place doesn't matter just consider initial and final state calculate delta H

There's energy in stability, if you recall The heat held there is the enthaply of the bond We're giving it potential since it's held in wait We could catalyse a reaction, move energy place to place

CHORUS

so compare those enthalpies for each compound did more energy go in or more energy come out? subtract initial's formation from the final, what remains might be positive or negative, but that's your enthalpy change!

CHORUS

So Hess's Law actually just says that the net heat change of a reaction is the sum of all sub-changes. This song is mostly about how you can calculate enthalpy change using the enthalpy of formation, which is sort of a special case? Or rather, an extension of Hess's law.