title: Solids, Liquids, And Gases (Rookie Read-About Science)
author:  Ginger Garrett 
description: Ginger Garrett is the author of several nonfiction books for children.
zlib_text: Chapter 4
  Gases and Vapors
  Gases and vapors are naturally associated with foods and food-processing systems. The equilibrium
  between food and water vapor determines temperatures achieved during processing. Dissolved gases
  in foods such as oxygen affect shelf life. Gases are used to ﬂush packages to eliminate oxygen and
  prolong shelf life. Modiﬁed atmospheres in packages have been used to prolong shelf life of packaged
  foods. Air is used for dehydration. Gases are used as propellants in aerosol cans and as refrigerants.
  The distinction between gases and vapors is very loose because theoretically all vapors are gases. The
  term “vapor” is generally used for the gaseous phase of a substance that exists as a liquid or a solid at
  ambient conditions.
  4.1
  EQUATIONS OF STATE FOR IDEAL AND REAL GASES
  Equations of state are expressions for the relationship between pressure, volume, temperature and
  quantity of gases within a given system. The simplest equation of state, the ideal gas equation, clo