It is often more convenient for us to group objects into defined units of measure for calculations. For example roses and eggs are commonly sold in units of 12, a dozen.
Chemists use the unit of a mole to group atoms, molecules, or other things into workable units. If you have a mole of something, that means that you have 602,204,500,000,000,000,000,000 of it. To make it easier to write we usually use scientific notation and say that we have 6.022 x 10^{23} things.
The Avogadro constant 6.022 10^{23} is defined as the number of atoms in exactly 12 g of carbon-12. The mole is the amount of substance that contains the same number of particles (atoms/ ions/ molecules/ formula units etc.) as there are atoms in exactly 12 g of carbon-12. Mass of 1 mole of a substance is called its molar mass.
Boyle's Law states that Volume of a given mass of dry gas is inversely proportional to its pressure at a constant temperature
Charle's Law is Volume of a given mass of a dry gas is directly proportional to its absolute (kelvin) temperature, if the pressure is kept constant.
Guy-Lussac's Law of combining Volumes states that when gases react, they do so in volumes which bear a simple ratio to one another, and to the volume of gaseous product, provided that all the volumes are measured at the same temperature and pressure.
Avogadro's Law : Equal volumes of all gases under similar conditions of temperature and pressure contain the same number of molecules We'll enhance our knowledge on atomic mass, evaluation of percentage composition of a compound in a reaction etc. in this module.