# Chapter5 - Chapter 5 The Gaseous State CHM1045C Dr Diego J...

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1/27/20111Chapter 5 The Gaseous StateCHM1045CDr. Diego J. DíazText: General Chemistry 9thEd. by Ebbing & GammonThe gaseous state is know for several of its properties. A gas is compressible, it does not have a definite shape and it is a fluid.One more important thing about gases it that their behavior can be described by using several relations or gas laws.Properties of GasesPressure– force exerted per unit area of surface. SI unit for pressure is the pascal (Pa).1 Pa = 1 kg /(m s2)Barometer– device used for measuring the atmospheric pressure.Manometer– device used for measuring the pressure of a gas or a liquid in a containerUnits to measure pressure:millimeters of mercury (mmHg) or torr– pressure equal to the one exerted by a column of mercury 1mm high at 0.0 °C.Pascal (Pa) –1 kg/(m∙s2)atmosphere (atm)– 760 mmHg = 1.01325 x 105PaBar– 1.0 x 105Pa ( 1.03125 Bar = 1 atm)P = g d h
1/27/20112BarometerManometerBoyle’s LawIn the 17thcentury Robert Boyle found that when the pressure of a gas was increased the volume decreased. When the pressure decreased, the volume increased.Boyle’s Law: The volume of a sample of a gas at a given temperature varies inversely with the applied pressure.g1842g1848g3404g1855g1867g1866g1871g1872g1853g1866g1872g4666g1853g1872g1853g1858g1861g1876g1857g1856g1872g1857g1865g1868g1857g1870g1853g1872g1873g1870g1857g4667
1/27/20113At a fixed temperature, if the pressure of the gas is changed, the volume will change according to the relation:g1842g3033g1848g3033= g1842g3036g1848g3036if the temperature is kept constant.Exercise 5.2, Problem 5.40Charle’s LawIn the 18thcentury Jacques Charles found that when the temperature of a gas is increased while keeping the pressure constant, the volume of the gas will increase linearly with the temperature.Charle’s Law: The volume occupied by any sample of gas at a constant pressure is directly proportional to the absolute temperature.g1842g1846g3404g1855g1867g1866g1871g1872g1853g1866g1872g4666g1853g1872g1853g1858g1861g1876g1857g1856g1868g1870g1857g1871g1871g1873g1870g1857g4667Exercise 5.3, Problem 5.46g3017g3281g3021g3281=g3017g3284g3021g3284Most gases follow Charle’s and Boyle’s law except at high pressure and low temperature!