Iso-octane is used in gasoline/automobile engineering as a standard, with an "octane rating" of 100. The standard molar enthalpy of formation of iso-octane C8H18(l) is -223.8 kJ/mol. For the balanced reaction equation of octane use: C8H18(l) + 12.5O2 --> 8CO2 + 9H2O.

Octane is a liquid, but all the other chemicals in this reaction are gases. What is the enthalpy change of this reaction in kJ/mol?

The characteristics of two different types of reactions are shown below: reaction a: electrons are gained by the atoms of an element. reaction b: protons are lost by the atom of an element. which statement is true about the atoms of the elements that participate in the two reactions? their identity changes in both reaction a and reaction b. their identity changes in reaction a but not in reaction b. their identity changes in reaction b but not in reaction a. their identity remains the same in both reaction a and reaction b.