For a particular isomer of c8h18,c8h18, the combustion reaction produces 5099.5 kj 5099.5 kj of heat per mole of c8h18(g)c8h18(g) consumed, under standard conditions. c8h18(g)+252o2(g)⟶8co2(g)+9h2o(g)δh ∘rxn=−5099.5 kj/mol c8h18(g)+252o2(g)⟶8co2(g)+9h2o(g)δh rxn°=−5099.5 kj/mol what is the standard enthalpy of formation of this isomer of c8h18(g)

Answer : The standard enthalpy of formation of this isomer of is -222 kJ/mol

Explanation :

Enthalpy change : It is defined as the difference in enthalpies of all the product and the reactants each multiplied with their respective number of moles. It is represented as

The equation used to calculate enthalpy change is of a reaction is:  

The equilibrium reaction of combustion of follows:

The equation for the enthalpy change of the above reaction is:

We are given:

Putting values in above equation, we get:

Therefore, the standard enthalpy of formation of this isomer of is -222 kJ/mol

your answer would be a. 12.5 kg