شرح درس
The Mole
CHEMISTRY - Secondary 1
In This part we will study
Calculation the number of moles
We can calculate the number of moles by using the following relation:

Number of moles (mol) = "Mass of substance (g)" /"Molar mass (mass of one mole) (g/mol)"

Example (1) :
Calculate the number of moles of carbon atoms in a sample of it, its mass equals 144 g
(C= 12)
Solution :
Number of moles of carbon atoms = "Mass of carbon" /"Molar mass of carbon" = "144" /"12" = 12 mol
Example (2) :
Calculate the number of moles of water found in 36 g of it. [H = 1, 0=16]
Solution :
The molar mass of H2O = (2 x 1) + 16 = 18 g/mol
The number of moles of water = 36/18 = 2 mol
Calculations of gram mass and molar mass in chemical reactions
The unknown gram mass of one of the reactants or the products in a chemical reaction can be calculated in a balanced symbolic equation by knowing the gram mass of another reactant or product and the molar masses of both of them.

Example (1) :
Calculate the mass of calcium oxide produced from the decomposition of 10 g of calcium carbonate. [Ca= 40 , C = 12 , O = 16]
Solution :

The produced mass of calcium oxide = (10 x 56)/100 = 5.6 g
Example (2) :
Calculate the mass of oxygen which is required for complete reaction with 27 g of aluminum.
[O = 16, Al = 27]
Solution :

The produced mass of calcium oxide = (27 x 96)/108 = 24 g
Example (3) :
When modern cars collide with a wall, air bags are inflated with nitrogen gas, as a result of these two following reactions:

Calculate the total number of moles of nitrogen gas which are produced from decomposition of ( 1 mol ) of sodium azide NaN3 in excess KNO3

Best wishes to you
Mr.Ahmed Elbasha

كيمياء الصف الاول الثانوي لغات - الفصل الدراسي الاول
شرح كيمياء لغات اولي ثانوي - مستر احمد الباشا
كيمياء لغات - الصف الاول الثانوي - كيمياء اولي ثانوي الترم الاول - كيمستري اولي ثانوي الترم الاول