chemistry question

Question

For a particular isomer of C8H18, the combustion reaction produces 5099.5 kJ of heat per mole of C8H18(g) consumed, under standard conditions.

C8H18(g)+252O2(g)⟶8CO2(g)+9H2O(g)ΔH∘rxn=−5099.5 kJ/mol

What is the standard enthalpy of formation of this isomer ofC8H18(g)?

ΔH∘f = _____ kJ/mol

Answer 1

This is the same as previous questions in that the ∆Hºrxn is equal to ∑∆Hºproducts - ∆Hºreactants.

Look up the ∆Hº values for the products and multiply by their respective coefficients and add them up.

Look up ∆Hº values for reactants and multiply by respective coefficients and add them up.Of course, the value for C8H18 will be X or unknown as this is what you are solving for.

Then... products - reactants = -5099.5 and solve for X