Given the following heats of formation. Calculate the heat of combustion of each compound in kJ mole -1 . The product in each case
will be CO 2(g) and H 2 O (l) .
(a) ethane, C 2 H 6(g) , -107 kJ mole -1
(b) acetylene, C 2 H 2(g) , +227 kJ mole -1
(c) benzoic acid, C 7 H 6 O 2(s) , -390 kJ mole -1

definition

                    entropy is a measure of the randomness or the extent of disorder of a chemical process.

                      enthalpy is a measure of the heat change of a reaction occurring at a constant pressure.

measurement units:

                        entropy is measured in joule per kelvin (jk⁻¹)   whereas enthalpy is measured in joule per mole (jmol⁻¹)

requirements:

                            entropy has no requirements or limits, and its change is measured by the division between the heat change of the chemical process and the temperature.

                              in contrast, enthalpy can only be related to the heat change of the reaction under standard conditions.