## Physics Of Hyperbaric Pressure

Wilhelm Welslau

Gesellschaft für Tauch- und Überdruckmedizin [German Society for Diving and Hyperbaric Medicine]

Abstract: Within the scope of this book, a review is presented regarding general characteristics of gases: constants, pressure and density, composition of air, and characteristics of oxygen, nitrogen and carbon dioxide as major components of air. Relevant information is given regarding the basic gas laws of Boyle and Amontons, the universal gas equation, the gas laws of Dalton and Henry and the laws of diffusion (Fick). In addition the principle of adiabatic processes (Joule-Thomson effect and adiabatic decompression) is described

Keywords: mol, molecular weight, Avogadro's number, Loschmidt's number, Avogadro's law, pressure, pressure unit, density, air, oxygen, nitrogen, carbon dioxide, Boyle's law, Boyle Mariotte law, Amontons' law, Graham's law, ideal gas law, universal gas equation, Dalton's law, partial pressure, fraction, Henry's law, Bunsen's solubility coefficient, diffusion, Fick's First Law of Diffusion, Fick's Second Law of Diffusion, adiabatic process, Joule-Thomson effect, adiabatic compression, adiabatic decompression

1. CHARACTERISTICS OF GASES

1.1 Basics

### Molecular weight

1 mole of a substance (atoms, ions, molecules, or formula units) is defined as the molecular weight of the substance in grams, e.g. 1 mole of oxygen (O2, molecular weight 32), weighs 32 grams.

Avogadro's number

Avogadro's number (6.022 x 1023) is approximately the number of particles (atoms, ions, molecules, or formula units) contained in 1 mole of a

substance. In German-speaking countries this constant is also known as Loschmidt's number.

Avogadro's law

Avogadro's law states that equal volumes of gases, at the same temperature and pressure, contain equal numbers of molecules. At standard conditions (0°C, 1.013bar) the volume of any gas is 22.42 l/mol.

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