Mole concept and its applications.


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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