Thursday 22 January 2015

7.3.2 - Laboratory Activity : Preparation of solution of certain concentration using the dilution method


Laboratory Activity 7.3.2:
Preparation of solution of certain concentration using the dilution method
Aim: To prepare standard solution of hydrochloric acid, 0.2mol dm-3 , 0.02mol dm-3 and 0.002mol dm-3 through the dilution of hydrochloric acid standard solution, 2mol dm-3.
Material:
» Hydrochloric acid 2mol dm-3
» Distilled water

Apparatus:
» Volume flask (100cm3)
» Pipette (10cm3) with pump
» Filter funnel
Procedure:


1. 100cm3 volumetric flask is used in this experiment. Determine the amount of volume of hydrochloric acid of that need to used to produce a diluted hydrochloric acid of 0.2mol dm-3 by using the dilution equation.

M1V1=M2V2
2×V1=0.2×100
V1=0.2×1002
V1=10cm3
2. 10cm3 of 2mol dm-3HCl is transferred from the given solution into a 100cm3 volumetric flask by using pipette.
3. Distilled water is added to the 100cm3 mark; the flask is then closed and inverted for few times until the solution is well mixed. A 0.2mol dm-3HCl solution is obtained.
4. To prepare 100cm3 of 0.02mol dm-3HCl, step 2 and 3 are repeated using 10cm3 of 0.2mol dm-3HCl.
5. To prepare 100cm3 of 0.002mol dm-3HCl, step 2 and 3 are repeated using 10cm3 of 0.02mol dm-3HCl.
Results:

Molarity of initial acid M1, mol dm-3 Initial volume used V1/cm3 Final volume used V2/cm3 Molarity of final acid M2, mol dm-3
2.0 10 100 0.2
0.2 10 100 0.02
0.02 10 100 0.002
Conclusion:

Hydrochloric acid of varying molarities can be prepared by diluting a standard solution, 2 mol dm-3.


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