STD X – MOLE CONCEPT AND STOICHIOMETRY – NEWTON

Avogadros Law and Gay Lussacs Law

The gas laws were developed at the end of the 18th century when scientists began to realise that relationships between the pressure, volume, and temperature of a sample of gas could be obtained which would hold to a good approximation for all gases.

Gases behave in a similar way over a wide variety of conditions because they all have molecules which are widely spaced, and the equation of state for an ideal gas is derived from kinetic theory.

Avogadro’s law:

Amedo Avogadro proposed this law in the year 1811. Avogadro’s Law states that the volume occupied by an ideal gas is directly proportional to the number of molecules of the gas present in the container.

Gay Lussac’s law:

Gay-Lussac’s Law was found by Joseph Louis Gay-Lussac in 1809. It states that, for a given mass and constant volume of an ideal gas, the pressure exerted on the sides of its container is directly proportional to its absolute temperature.

Mole Concept

The mole is the unit of measurement in the International System of Units (SI) for an amount of substance. The number of molecules per mole is known as Avogadro’s constant and is defined such that the mass of one mole of a substance, expressed in grammes, is equal to the mean relative molecular mass of the substance.

Percentage composition,Empirical and Molecular formulae

The percentage by mass of each element present in a compound is given by percentage composition.

The simplest ratio of the whole numbers of atoms of different elements present in one molecule of the compound is given by the simplest formula known as the Empirical formula. With the help of empirical formula, we can calculate the empirical mass of the compound.