Reference States, Heats of Mixing and Solution Reference Page
Reference Not Found: Mixing, Dissolving, and Changing the Rules

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Intro to Reference Not Found: Mixing, Dissolving, and Changing the Rules

Thermodynamic properties such as internal energy and enthalpy cannot usually be measured in an absolute sense. Instead, they are defined relative to a reference state.

Once a reference state is chosen, energy changes can be calculated consistently for processes such as mixing, dissolving, heating, or reacting. This video explains how reference states work and how they affect quantities such as heats of mixing and heats of solution.

Reference Not Found: Mixing, Dissolving, and Changing the Rules

This video explains how thermodynamic reference states are defined and shows how they influence calculations involving mixing and dissolution processes.

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Examples and Definitions

Definitions

Reference State
A specified state of a substance—usually defined by temperature, pressure, and phase—to which thermodynamic properties are referenced.

For example, it is common to reference the internal energy of ice, liquid water, and steam to liquid water at the triple point of water, 273.16 K and 611.657 Pa.

Heat or Enthalpy of Solution, \(\Delta \hat{H}_s\)
The enthalpy change associated with dissolving a fixed amount of solute in a solvent at constant pressure, usually at constant temperature.
Heat or Enthalpy of Mixing, \(\Delta \hat{H}_m\)
The enthalpy change associated with mixing fixed amounts of two or more substances at constant pressure, usually at constant temperature.