explain mole concept and stoichiometry icse chemistry
Answers
A mole (symbol mol) is defined as the amount of substance that contains as many atoms, molecules, ions, electrons or any other elementary entities as there are carbon atoms in exactly 12 gm of . The number of atoms in 12 gm of is called Avogadro's number .
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 1023 things.
The Avogadro constant 6.022 1023 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.