MOLE AND ITS APPLICATIONS
( Mole is the SI unit of quantity of matter.
Mole is a chemical unit only
( It is the mass in grams of 6.02 x 1023 particles of a substance. i.e atoms , molecules or ions of the substance.
( The mass in grams of 6.02 x 1023 particles of a substance is equal to its atomic mass or molecular mass. Therefore
( Atomic mass, Molecular mass or Formula mass is called Gram atom or gram molecule and is also called mole and contain 6.02 x 1023 particles.
( Symbol of mole is mol
( The number 6.02 x 1023 is called Avogadros number in the honour of Italian Scientist Amedo Avogadro. Its symbol is NA
1 mole C = 12g = 6.02 x 1023 atoms.
1 mole Na = 23g = 6.02 x 1023 atoms
1 mole H2O = 18g = 6.02 x 1023 molecules
1 mole C12H22O11 = 342g = 6.02 x 10 23 molecules
APPLICATIONS
Conversion of Gram to mole & vise versa.
For this inter conversion the formula is Mole =
Or M = or weight in g = Mole x At.wt
= Mole x M.wt
POINT TO REMEMBER
If equal quantity of different substance is given. The one which has higher molar mass
will have less mole and less number of particles.
Example: Convert 0.1g Na to mole.
As = mole = = = 0.0043 or 4.3 x 103 mole
Example: Convert 103 moles of MgSO4 to gram.
F.wt of MgSO4 = 24 + 32 + 64 = 120
Mole = or wt in g = Mole x F.wt
= 103 x 120 = 0.12g
Example: Calculate the number of mole in 50g H2O.
M.Wt of H2O = 18g/mole
Moles = = = 2.7 moles
Example: How many moles of He are in 6.46g of He.
At.wt of He = 4.003g/mol
Mole = = = 1.61 moles
Example: How many gram of Zn are there in 0.356g Zn
At.wt of Zn = 65.39g
Wt in g = Mole x M.wt = 0.356 x 65.39 = 23.3g
2. MOLE TO MOLECULES AND VISE VERSA
For the inter conversion of mole to molecule & vise versa the formula used is
Mole =
Example: How many molecules are there in 1.5 moles of water.
As mole =
No of particles = mole x NA
= 1.5 x 6.02 x 1023 = 9.03 x 1023 molecules
Example: How many moles are there in 6.02 x 1020 molecules of water?
Mole =
= = 103 moles
Example: How many atoms and mass in g are there in 1.25 moles of Na
(1) Atoms = As 1 mol Na contain atoms = 6.02 x 1023
1.25 mole Na contain atoms
= 1.25 x 6.02 x 1023 = 7.25 x 1023 atoms
(2) Mass in g
1 mole of Na = 23g
1.25 moles of Na = 23 x 1.25 = 28.75g
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