Question

what is the theoretical basis for the mole concept used in chemistry?

Answer 1

Mole concept used in chemistry:

Definition of Mole:

It is the amount of the substance of a system that contains as many elementary entities as there are atoms in 0.012kg of Carbon-12.

Mole:

• As molecules and atoms are too small to count, their numbers are expressed in terms of Avogadro's number (N_A = 6.023*10²³).
• Mole is anumber which is equal to Avogadro's number. So mole is defined as a unit which represents 6.023*10²³ particles of same matter.
• The symbol of mole is "mol".
• The importance of mole concept used is to make the calculations easy.

Applications of Mole Concept:

Although mole is defined as number it has some other eqivalent definitions. The mole is defined for different states of matter and at different conditions as:

• In terms of particle, 1 Mole = 6*10²³ particles
• In terms of volume, 1 Mole = 22.4 L of gas at N.T.P or molar volume.
• In terms of mass, 1 Mole = 1 gram atom of, 1 Mole = 1 gram mole of , 1 Mole = 1 gram formula of mass substance.

Formulas to calculate the number of moles:

The number of moles can be calculated in different ways as:

1. Number of moles of molecules = (weight in gram) / (moleculear mass)
2. Number of moles of atoms = (weight in gram) / (atomic mass)
3. Number of moles of gases = (volume at STP) / (standard molar volume)
4. Number of moles of particles like atoms, molecules, ions = (number of particles) / (avgadro's number).

Moles is also used to express the concentration of the solution in terms of molarity, molality, mass fraction.