Gas Solubility

5 Key excerpts on "Gas Solubility"

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  eBook - ePub

  The Britannica Guide to Matter

  • Britannica Educational Publishing, Erik Gregersen(Authors)
  • 2010(Publication Date)
  • Britannica Educational Publishing

    (Publisher)

  CHAPTER 5 LIQUID SOLUTIONS AND SOLUBILITY

  T he ability of liquids to dissolve solids, other liquids, or gases has long been recognized as one of the fundamental phenomena of nature encountered in daily life. The practical importance of solutions and the need to understand their properties have challenged numerous writers since the Ionian philosophers and Aristotle. Many physicists and chemists have devoted themselves to a study of solutions.

  A solution is a mixture of two or more chemically distinct substances that is said to be homogeneous on the molecular scale—the composition at any one point in the mixture is the same as that at any other point. This is in contrast to a suspension (or slurry), in which small discontinuous particles are surrounded by a continuous fluid. Although the word solution is commonly applied to the liquid state of matter, solutions of solids and gases are also possible. Brass, for example, is a solution of copper and zinc, and air is a solution primarily of oxygen and nitrogen with a few other gases present in relatively small amounts.

  The ability of one substance to dissolve another depends always on the chemical nature of the substances, frequently on the temperature, and occasionally on the pressure. Water, for example, readily dissolves methyl alcohol but does not dissolve mercury; it barely dissolves benzene at room temperature but does so increasingly as the temperature rises. While the solubility in water of the gases present in air is extremely small at atmospheric pressure, it becomes appreciable at high pressures where, in many cases, the solubility of a gas is (approximately) proportional to its pressure. Thus, a diver breathes air (four-fifths nitrogen) at a pressure corresponding to the pressure around him, and, as he goes deeper, more air dissolves in his blood. If he ascends rapidly, the solubility of the gases decreases so that they leave his blood suddenly, forming bubbles in the blood vessels. This condition (known as the bends) is extremely painful and may cause death; it can be alleviated by breathing, instead of air, a mixture of helium and oxygen because the solubility of helium in blood is much lower than that of nitrogen.

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  eBook - ePub

  Environmental Engineering

  Principles and Practice

  • Richard O. Mines(Author)
  • 2014(Publication Date)
  • Wiley-Blackwell

    (Publisher)

  The carbonate system is the most important natural buffering system encountered in environmental engineering. It is directly related to alkalinity, which is defined as the buffering capacity of a water to resist a change in pH when an acid is added.

  • Alkalinity is measured by titrating a sample of water with to a pH of approximately 4.5.
  • Mathematically, alkalinity is defined by the following equation:
• Liquid-solid species that are partially soluble or insoluble can be explained using the solubility product The solubility of most substances increases with temperature; however, there are exceptions:
  • Salts with low values generally have low solubilities.
  • It is impossible to predict the solubilities of various compounds solely based on values since solids that dissolve into two or three ions will generally have higher solubilities.
• Proper application of gas phase laws is essential for designing gas transfer systems, gas strippers, determining saturation concentration of dissolved gases in aqueous solutions, and understanding the relationship between pressure and volume of a gas and between temperature and volume of a gas.
  • The ideal gas law is used to solve for pressure, volume, moles, or temperature, given three of these four parameters.
  • Dalton's law of partial pressure states that the total pressure exerted by a mixture of gases is the sum of the partial pressures of each gas present.
  • Raoult's law relates the partial pressure of the gaseous component present above a liquid to the vapor pressure of the pure component and the mole fraction of the pure component in the liquid phase.
  • Henry's law is used for calculating the solubility of a gas in a liquid, or to describe the equilibrium condition between the gas and liquid phases.
  • There are several forms of Henry's law, so special attention should be placed on the dimensions on the Henry's law constant in order to apply the appropriate equation expressing Henry's law.
• Organic chemistry is the study of carbon-containing compounds and their properties. Organic compounds are important because: they form the basis of all life; they are used in the production of pesticides, herbicides, insecticides, polymers, antibiotics, hormones, and alcohols; and they cause detrimental affects to the environment, since many of them are toxic and/or carcinogenic.