Freezing-point depression
Amount by which a given quantity of solute lowers the freezing point of a liquid. A colligative
property.
Galvanic cell
An electrochemical cell that uses a spontaneous redox reaction to do work, i.e., produce an
electrical current. Also called a Voltaic cell.
Gamma (γ) radiation
High-energy photons often emitted in radioactive decay.
Gas
The physical state of matter possessing a high degree of disorder, in which molecules interact only
slightly; found at relatively low pressure and high temperatures. Also called vapor. See Ideal gas.
Gas constant (R)
A proportionality constant that appears in the ideal gas law, PV = nRT. Its value depends upon the
units of pressure, temperature, and volume used in a given situation.
Geiger counter
An instrument used to measure radioactivity.
Gibbs free energy (G)
The energy of a system available to do work. The change in Gibbs free energy, ∆G, is determined for
a given reaction from the equation ∆G = ∆H – T∆S. ∆G is used to predict the spontaneity of a
reaction: A negative ∆G denotes a spontaneous reaction, while positive ∆G denotes a
nonspontaneous reaction.
Graham’s law