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An italic capital H, internal energy plus pressure times volume.
Also known as: Enthalpy, Heat content, Heat function
Enthalpy is internal energy with the work of pushing the atmosphere aside already added in, which is why reaction heats measured in an open beaker are enthalpy changes rather than energy changes. Only differences in it are measurable; the absolute value is not.
Denotes enthalpy, defined as internal energy plus the product of pressure and volume.
Contexts: Laboratory
Equals the heat absorbed at constant pressure, which is why it is the quantity tabulated for chemical reactions.
Contexts: Laboratory
Has no absolute zero point in practice; only enthalpy changes are measured, which is why tables give values relative to a standard state.
Contexts: Laboratory
An italic capital letter H, two vertical strokes joined by a horizontal bar at mid-height.