Mole Concept

DAY 1     6th period

21.4.20

Good Afternoon Boys,

Learning Objective :

students will be able to


Define Mole
Apply Mole concept to numericals.




Notes and numerical have to be copied in your notecopy.
Mole 

It is defined as  a unit which represents 6.023 x1023 particles of same matter.


A mole (symbol mol) is defined as the amount of substance that contains as many atoms, molecules, ions, electrons or any other elementary entities as there are carbon atoms in exactly 12 gm of carbon

























  






















Question 1: Calculate the mass of (i) an atom of silver (ii) a molecule of carbon dioxide.


Solution:




1 mole of Ag atoms = 108 g        




           = 6.022 x 1023 atoms


           6.022 x 1023 atoms of silver have mass = 108g


            Mass of one atom of silver




1 mole of CO2 = 44 g    




           = 6.022 x 1023 molecules


           Thus, 6.022 x 1023 molecules of CO2 has mass = 44 g


            1 molecule of CO2 has mass = 7.307 ´x 10-23 g


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Question 2:  Calculate the number of molecules present




in 34.20 grams of cane sugar (C12H22O11)








in one litre of water assuming that the density of water is 1 g/cm3








in one drop of water having mass 0.05 g.




Solution:




1 mole of C12H22O11 = 342 g




           = 12 x 12 + 22 x 1 + 11 x 16 = 342 amu


           = 6.022 x 1023 molecules


           Now 342 g of cane sugar contain 6.022 x 1023 molecules.


            34.2 g of cane sugar will contain


           = 6.022 x 1022 molecules




1 mole of water = 18 g = 6.022 x 1023 molecules.

Mass of 1 litre of water = Volume x density = 1000 x 1 = 1000 g



           Now 18 g of water contains = 6.022 x 1023 molecules.


           1000 g of water will contain = 3.346 x 1025 molecules




1 mole of H2O = 18 g = 6.022 x 1023 molecules.






           Mass of 1 drop of water = 0.05 g


           Now 18 g of H2O contain = 6.022 x 1023  molecules.


           0.05 g of H2O will contain = 0.016 x 1023  molecules.


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Question 3: Calculate the number of moles in each of the following:




392 grams of sulphuric acid








44.8 litres of carbon dioxide at STP








6.022 x 1023 molecules of oxygen 

 9.0 grams of aluminium
  1 metric ton of iron (1 metric ton = 103 kg )
  7.9 mg of Ca 

Solution:




1 mole of H2SO4 = 98 g




           Thus 98 g of H2SO4 = 1 mole of H2SO4


           392 g of H2SO4 =  = 4 moles of H2SO4




1 mole of CO2 = 22.4 litres at STP






           i.e. 22.4 litres of CO2 at STP = 1 mole


           44.8 litres of CO2 at STP = 2 moles CO2




1 mole of O2 molecules = 6.022 x 1023 molecules.





            6.022 x 1023  molecules = 1 mole of oxygen molecules.




1 mole of Al = 27 g of Al


i.e. 27 g of aluminium = 1 mole of Al


            9 g of aluminium =   0.33 mole of Al




1 metric ton of Fe = 103 kg = 103000g






            1 mole of Fe = 56 g of Fe


            103000 g of Fe = 1.839 x 102  moles




7.9 mg of Ca = 7.9x 10-3 g of Ca


Thats All for the day.

Stay safe 

Take care




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