Hello I was hoping you could please explain the difference between enthalpy and heat. They seem to be the exact same thing in the math but the book is saying they are distinct. Thank you
This is a great question. Here is (hopefully) an answer that might clarify some of your confusion:
For the most part, the enthalpy of a compound can be regarded as the energy contained within its bonds, or its internal energy. It can be reasoned that the enthalpy and internal energy of a compound increase with increasing temperature. On the other hand, heat is actually a way to measure the transfer of thermal energy. Therefore, one could state that the transfer of heat to a compound could increase its enthalpy.
But most of the time, enthalpy and heat tend be viewed as one and the same. Mathematically, enthalpy actually analyzes the change in internal energy as the volume of a system is changing at a constant P. However, we rarely work with a changing volume unless there is a combustion reaction that features a large disparity in the total moles of gas in the reactants vs. the total moles of gas in the products. Therefore, we can assume that delta H= delta U most of the time. And delta U increases with the addition of heat, which illustrates that heat and enthalpy are indeed closely related.
delta H= delta U + delta V (pressure)
Please let me know if any aspect of this explanation is unclear. :)
Hello Annabelle,
This is a great question. Here is (hopefully) an answer that might clarify some of your confusion:
For the most part, the enthalpy of a compound can be regarded as the energy contained within its bonds, or its internal energy. It can be reasoned that the enthalpy and internal energy of a compound increase with increasing temperature. On the other hand, heat is actually a way to measure the transfer of thermal energy. Therefore, one could state that the transfer of heat to a compound could increase its enthalpy.
But most of the time, enthalpy and heat tend be viewed as one and the same. Mathematically, enthalpy actually analyzes the change in internal energy as the volume of a system is changing at a constant P. However, we rarely work with a changing volume unless there is a combustion reaction that features a large disparity in the total moles of gas in the reactants vs. the total moles of gas in the products. Therefore, we can assume that delta H= delta U most of the time. And delta U increases with the addition of heat, which illustrates that heat and enthalpy are indeed closely related.
delta H= delta U + delta V (pressure)
Please let me know if any aspect of this explanation is unclear. :)