[taylor]

hey guys another thermo question. could anyone help me work out how i find out which of the following would produce the most heat per gram (if formed by there elements)
a)NO (g)
b)nitrogen dioxide (g)
c) hydrogen iodide (g)
d)C₆H₆
e) H₂S
thanks for any info

[nj_bartel]

convert to moles, find the heats of formation, compare

[taylor]

how do i calculate heat of formation because dont i need to compare the products to the reactants?

[BeepoGirl]

You shouldn't need to calculate standard enthalpy of formation for each they should be given in data tables in the form of per mole. Just convert it to grams and you're in.
Another route you could take would be using standard bond enthalpies ( also given in data tables) but this would be more unreliable as they are just an average enthalpy of a bond.