Q7 of 24 Page 166

Fill in the blanks using the given data:

The formula of Calcium oxide is CaO. The atomic mass of Ca is 40, Oxygen is 16 and Carbon is 12.


i) 1 mole of Ca ( ____g) and 1 mole of Oxygen atom ( ___g) combine to form _____mole of CaO ( ____g).


ii) 1 mole of Ca ( ___g) and 1 mole of C ( ___g) and 3 moles of Oxygen atom ( ___g) combine to form 1 mole of CaCO3 ( ___g)

i) 1 mole of Ca ( 40 g) and 1 mole of an Oxygen atom ( 16 g) combine to form 1 mole of CaO ( 56 g).


ii) 1 mole of Ca ( 40 g) and 1 mole of C ( 12 g) and 3 moles of an Oxygen atom ( 3x16 = 48 g) combine to form 1 mole of CaCO3 ( 100 g)


Note:


1. If a compound or molecular substance is taken, like CO2, N2 etc, then 1


a mole of the substance contains Avogadro number of molecules. 1 mole contains the mass equal to the molecular weight of the substance.


2. If an element is taken like C, S, Fe, then 1 mole contains Avogadro


number of atoms. 1 mole contains the mass equal to the atomic weight of the substance.


So, 1 mole of Ca is 40 grams, 1 mole of O atom is 16 grams and 1 mole of C is 12 grams of C. 1 mole of CaO is 56 grams (40+16) of CaO and 1 mole of CaCO3 is 100 grams ( 40+12+48).


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