Elements or compounds participate in reactions by means of their
molecules and not atoms.This was postulated and proved by Avogadro.
The molecules are composed of atoms of same or different elements. In case of monatomic molecules of elements,there is no difference between the composition of molecule and atom.
The mass of the molecule is mass of constituent atoms which in turn is the mass of those atoms.
Therefore it can be said that the mass of a molecule is the sum of masses of protons and neutrons in the molecule.This is molar mass.The molar mass units is a.m.u.
What is the significance of the mass of the molecule and how is it related to mole or molar....?
A mole is molar mass expressed in terms of g.
It was proved by Avogadro that when the elements or compounds enter into a reaction,they do so not by their pure mass,but by the mass expressed in terms of grams.
e.g.
Formation of ammonia
N2 + 3H2 ---------> 2NH3
As mentioned above, it is not that 1g of nitrogen would combine with 3 g of hydrogen to form 2 g of ammonia.
However it is that 1mole of nitrogen would combine with 3 moles of hydrogen to form 2 moles of ammonia.
All the properties of compounds are related to moles or molar quantities.
In the beginning the energy supplied is used to increase the energy of the molecules in the same liquid phase.The heat energy supplied from outside is utilised to increase the vibrating energy of the molecules which is noticed in form of rise in the temperature of the water.
In the second phase,the energy absorbed by the molecules, after reaching a threshold, no longer is used to increase the temperature but breaking the intermolecular attractions.
The intermolecular forces are overcome at a specific temperature which is called as boiling point.The liquid molecules which overcome these intermolecular forces turn into gas phase [steam].This process is called vaporization
The energy supplied beyond this boiling point is not utilized to increase the temperature but to overcome the intermolecular forces,by more and more number of molecules.As a result they vaporize accordingly.
When quantified, it was found that the energy required to vaporize a mole of water,called, molar heat of vaporization of water, is is 49.79 kJ/mole.
In other words,to vaporize one mole of water energy required is 49.79 kJ.
The molecules are composed of atoms of same or different elements. In case of monatomic molecules of elements,there is no difference between the composition of molecule and atom.
The mass of the molecule is mass of constituent atoms which in turn is the mass of those atoms.
Therefore it can be said that the mass of a molecule is the sum of masses of protons and neutrons in the molecule.This is molar mass.The molar mass units is a.m.u.
What is the significance of the mass of the molecule and how is it related to mole or molar....?
A mole is molar mass expressed in terms of g.
It was proved by Avogadro that when the elements or compounds enter into a reaction,they do so not by their pure mass,but by the mass expressed in terms of grams.
e.g.
Formation of ammonia
N2 + 3H2 ---------> 2NH3
As mentioned above, it is not that 1g of nitrogen would combine with 3 g of hydrogen to form 2 g of ammonia.
However it is that 1mole of nitrogen would combine with 3 moles of hydrogen to form 2 moles of ammonia.
All the properties of compounds are related to moles or molar quantities.
Heat of Vaporization
Whenever a water is heated to a certain temperature, it undergoes two changes.In the beginning the energy supplied is used to increase the energy of the molecules in the same liquid phase.The heat energy supplied from outside is utilised to increase the vibrating energy of the molecules which is noticed in form of rise in the temperature of the water.
In the second phase,the energy absorbed by the molecules, after reaching a threshold, no longer is used to increase the temperature but breaking the intermolecular attractions.
The intermolecular forces are overcome at a specific temperature which is called as boiling point.The liquid molecules which overcome these intermolecular forces turn into gas phase [steam].This process is called vaporization
The energy supplied beyond this boiling point is not utilized to increase the temperature but to overcome the intermolecular forces,by more and more number of molecules.As a result they vaporize accordingly.
When quantified, it was found that the energy required to vaporize a mole of water,called, molar heat of vaporization of water, is is 49.79 kJ/mole.
In other words,to vaporize one mole of water energy required is 49.79 kJ.
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