Dilution

  1. Dilution is a process of adding water to the standard solution lowered the concentration of the solution.
  2. In dilution of solution, we should take note that mole of solute before dilution is equal to the mole of solute after dilution.

Number of mol of solute before dilution = Number of mole of solute after dilution
M 1 V 1 1000 = M 2 V 2 1000 or    M 1 V 1 = M 2 V 2
M1 = Molarity before dilution
M2 = Molarity after dilution
V1 = Volume before dilution
V2 = Volume after dilution


Example 1
100cm3 of 0.5 mol dm-3 sodium chloride solution is diluted with distilled water to produce 250 cm3 of solution. Calculate the concentration (in mol dm-3) of the sodium chloride solution after the dilution.

Answer:
M1 = 0.5 mol dm-3
M2 = ?
V1 = 100cm3
V2 = 250 cm3
M 1 V 1 = M 2 V 2 (0.5)(100)= M 2 (250) M 2 = (0.5)(100) 250 =0.2mol/d m 3

Example 2
Find the volume of 2 mol/dm3 nitric acid that needs to be diluted with distill water to produce 500cm3 of 0.05 mol/dm3 nitric acid.

Answer:
M1 = 2 mol dm-3
M2 = 0.05 mol/dm3
V1 = ?
V2 = 500 cm3
M 1 V 1 = M 2 V 2 (2) V 1 =(0.05)(500) V 1 = (0.05)(500) 2 =12.5c m 3



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