Question

Convert 87.69 kJ/g into k/mol?

Answer 1

Well you need the molar mass of the reagent....

Explanation:

And let us take an obvious example....the combustion of hydrocarbons...and we deal with that of methane for simplicity...

And thus...

`CH_4(g) + 2O_2(g) rarr CO_2(g) + 2H_2O(l) +Delta`

...This site quotes an enthalpy of combustion for methane of `-890*kJ*mol^-1`, and when we quote this, we MEAN per mole of reaction as written...i.e. the combustion of `16*g` of methane with stoichiometric dioxygen RELEASES `890*kJ`...

And thus `"PER GRAM of methane"`, we gets an energy output of `(-890*kJ)/(16*g)=-55.6*kJ*g^-1`...