It started out as:
The balanced equation is:
To balance this equation, I started with counting how many Hydrogens were on each
side (8 vs. 2), I then multiplied the H₂O on the products side by 4 to even those out.
C3H8+0₂=CO₂ + H₂O
Then I balance my metals (C in this case) by multiplying CO₂ by 3 to even those out,
then I would balance any nonmetals if they were any (there's not), so
I move on to my Oxygens. At this point, I have 2 on the reactants side and 10 on the
products side, so I multiply the O2 on the left side by 5 and voila! It's balanced.
Now you look at and add the enthalpy of formation of each of these compounds based
on what is in the tables.
On the reactants' side, ADD: C3Hg=-103.85,
50₂=5 x0=0
total =
On the products side, ADD: 3(CO₂) =3(-393.51) =_
PLUS 4(H₂O) = 4(-241.82)-
(A NEGATIVE PLUS A NEGATIVE IS A NEGATIVE)
total
Lastly, enthalpy of products (-2147.8)-enthalpy of reactants (-103.85)=
and therefore the reaction is thermic (releases energy).