Glossary

The enthalpyA thermodynamic state function, symbol H, that equals internal energy plus pressure x volume; the change in enthalpy corresponds to the energy transferred as a result of a temperature difference (heat transfer) when a reaction occurs at constant pressure. change when one moleThat chemical amount of a substance containing the same number of units as 12 g of carbon-12. of a compoundA substance made up of two or more elements and having those elements present in definite proportions; a compound can be decomposed into two or more different substances. is produced from its elements, each in their most stable form at a given temperatureA physical property that indicates whether one object can transfer thermal energy to another object. and standard pressureForce per unit area; in gases arising from the force exerted by collisions of gas molecules with the wall of the container. (1 bar). Also called standard heat of formationThe heat energy transfer into a system during the formation of one mole of a compound from its component elements in their most stable forms..