MOLE CONCEPT AND GASES, MOLE CONCEPT AND SOLUTION,
MOLE CONCEPT AND GASES:
One mole of any gas at room temperature and
pressure always occupy 24dm3 (24000 cm3) volume.
Volume of gas at r.t.p.
Number of moles of gas =
24dm3 (2400 cm3)
Whereas,
One mole of any gas at standard
temperature and pressure always occupy 22.4dm3
(22400 cm3)
volume.
Volume of gas at s.t.p
Number of moles of gas =
22.4dm3
(22400 cm3)
MOLE CONCEPT AND SOLUTION:
Concentration of solution is mostly expressed
in terms of molarity. It is the number is moles of solute and volume of solution expressed in dm3. Its unit are mole dm-3.
Number of moles of solute
Molarity =
Volume of solution in dm3
Mathematically;
M =
N = M x V (dm3)
n =
If we
put the value of mole in the Molarity expression.
Mole
Molarity =
Volume
as;
mole = mass / Mr
therefore;
Mass
/ Mr
Molarity =
Volume
Or
mass
Molarity =
Volume x Mr
Or
Mass / volume = Molarity x Mr
Concentration (grams dm-3) = Molarity x Mr
Thus
concentration of a solution has two units, one is mol.dm-3 which is
also called Molarity of the solution, and second is g.dm-3 which is
simple called concentration of the solution. In case of solution containing
ions made up of single element, the formula become;
Concentration (grams dm-3)
= Molarity x Ar
There is another important relation
which is used for calculation when concentrated solution is diluted to another
concentration.
M1V1 = M2V2
Where M1 and V1
stands for Molarity and volume of concentrated solution and M2 and V2
stand for Molarity and volume of diluted solution or vice versa.
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