what is enthalpy?

Asked by  | 2nd Jul, 2008, 07:53: PM

Expert Answer:

In thermodynamics and molecular chemistry, the enthalpy or heat content  is a quotient or description of thermodynamic potential of a system, which can be used to calculate the "useful" work obtainable from a closed thermodynamic system under constant pressure and entropy.

This is the heat change which occurs when 1 mol of a substance reacts completely with oxygen to form products at 298 K and 1 atm


where E represents the energy of the system. In the absence of an external field, the enthalpy may be defined, as it is generally known, by:

  • H is the enthalpy (joules)
  • U is the internal energy, (joules)
  • p is the pressure of the system, (pascals)
  • V is the volume, (cubic metres)



Answered by  | 3rd Jul, 2008, 12:56: PM

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