Question

Help, please. Use standard enthalpies of formation to calculate the true value of heat of formation of ZnO(s). [Zn(s)+1/2O2(g)---=>ZnO(s)].?
I can't figure out the step by step process for this, or even how to start and would like help.
I believe that standard enthalpie of ZnO(s) is -348.3
Zn: 130.4
and O2 : 0

Answer 1

Normally, you would goto you table w-4, get the enthalpies of each product and reactant.

Then you would just take the total heat of the products, and subtract from the reactants

products-reactants=heat of formation

in this case Zn(s) and O2(g) are both 0. So you would just get the formation heat of ZnO(s). Nothing to subtract by..

Answer 2

My bad I took the enthalpy of Zn(g) would that just make ZnO(s) -348.3 ?

Answer 3

My book says ZnO (s) is -350.5, but yeah, that's pretty close

Answer 4

thanks a bunch ! :)