Why required mole concept?
Atoms and molecules are very small so that to count the no. of atoms or molecules required one unit.
Mole concept is very easy way to represent the no. of molecules or atoms or ions present in given amount of substance.
To measure weight of body Kg is unit used.
To measure length of the road meter is unit used.
Like way measure no. of atoms or molecules present in substance required mole unit.
Avagadro Law
At same temperature and pressure same volumes of all gases contains same no. of molecules.
Means, if 1 volume of nitrogen gas contains n no. of molecules,
Then 1 volume of hydrogen gas also have n no. of molecules,
Also 1 volume of water vapour contains n no. of molecules at same temperature.
These number of molecules, atoms, ions expressed in mole.
Avogadro mention this number = 6.0221367 X 1023
This is known as Avogadro Constant.
It means that, 1 mole of oxygen containt = 6.0221367 X 1023 molecule of oxygen.
1 mole of NaCl containt =6.0221367 X 1023 molecule of NaCl.
How to calculate mole or convert mole into gram
Number of mole = Wt. of compound/ Molecular wt. of compound
calculate the no. of mole and no. of molecules present in 50gm sulfuric acid?
Convert 50 gm into mole of sulfuric acid.
Molecular wt. of H2SO4 = 98
Number of mole = wt. of sulfuric acid/ mol. wt. of sulfuric acid
No. of mole = 50gm/98 = 0.51 mol.
1 mol containt = 6.0221367X 1023 molecule
0.51 mol containt =0.51X 6.0221367X10 = 3.07 X 1023 molecules.
It means 50 gm sulfuric acid containt 0.51 mol of sulfuric acid and 3.07 x 1023 molecules.
Convert 2 mol into gram of oxygen,
mole = wt. of oxygen / molecular wt. of oxygen
2 = wt. of oxygen in gram/ 32
wt. of oxygen (gm) = 2 X 32 = 64 .
It means 2 mol oxygen equal to 64 gm of oxygen.
