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The relationship between the number of moles of a
substance with its mass
Relate to Avogadro Constant
Molar Mass
Meaning
2 kg of mangosteen
50 g of flower
3 kg of papaya
Amount of substanceMass
Mass of one mole of element or compound in gram
Molar mass
Unit
Gram per mol (g/mol)
MOLAR MASS OF AN ELEMENT
is found by looking at the atomic mass of the element on the periodic table
Molar mass = (RAM) Relative Atomic Mass= (RMM) Relative Molecular
Mass
Calcium = 40 g
Cobalt = 59g
Iron = 56 g
Bromine = 80g1 mole element
MOLAR MASS OF A CHEMICAL COMPOUND
Molar masses of chemical compounds are equal to the sums of the molar masses of all the atoms in one molecule of that compound
example : NaCl
molar mass = molar mass of one atom of sodium + molar mass of one atom of chlorine Answer : 58.5 g
EXAMPLE OF CHEMICAL COMPOUND
23g of sodium + 35g of chloride
=58 g
Water, H2O
Sodium Chloride, NaCl
2g hydrogen + 16g oxygen
= 18g
MOLAR MASS RELATION TO AVOGADRO CONSTANT
Molar mass = mass of 6.02 X 1023
1 mol = 6.02 X 1023
Molar mass = 1 mol mass
EXAMPLE
1 mol Aluminum has a mass of 27 g
1 mol of Aluminum contain 6.02 X 1023 atoms 6.02 X 1023 Atom of Aluminum has mass of 27g
Relative atomic mass
1 mole Aluminum
copper
watersulfur
1 mole - 18 g1 mole - 32 g
1 mole - 64 g
All this substance contain 6.02 X 1023
One mole of nails contains 6.022 x 1023 nails
One mole of screws contains 6.022 x 1023 screws
One mole of woods contains 6.022 x 1023 woods
Building of a house
SUBSTANCE
mol
Mass (g)
NA
He H2O NaCl
1 2
4.0 18.0 58.5
6.02 X 1023 6.02 X 1023
6.02 X 1023
1 Mol = 6.02 X 10 23
3
x 1 x 2 x 3
x 1 x 2 x 3