Gaseous State Introduction
Matter can be classified into three categories depending upon its physical state namely solid, liquid and gaseous states. Solids have a definite volume and shape; liquids also have a definite volume but no definite shape; gases have neither a definite volume nor a definite shape.
MEASURABLE PROPERTIES OF GASES :
Mass, volume, temperature are the important measurable properties of gases.
Mass: The mass of the gas is related to the number of moles as
n = w/M
Where n = number of moles
w = mass of gas in grams
M = molecular mass of the gas
Volume: Since gases occupy the entire space available to them, therefore the gas volume means the volume of the container in which the gas is enclosed.
Units of Volume: Volume is generally expressed in litre or cm3 or dm3 1m3 = 103 litre
= 103 dm3 = 106 cm3.
Pressure: The force exerted by the gas per unit area on the walls of the container is equal to its pressure.
Units of Pressure: The pressure of a gas is expressed in atm, Pa, Nm–2, bar or, lb/In2 (psi).
760 mm = 1 atm = 10132.5 KPa = 101325 Pa = 101325 Nm–2
760 mm of Hg = 1.01325 bar = 1013.25 milli bar = 14.7 lb/2n2 (psi)
Temperature: Temperature is defined as the degree of hotness. The SI unit of temperature is Kelvin. On the Celsius scale water freezes at 0°C and boils at 100°C where as in the Kelvin scale water freezes at 273 K and boils at 373 K.