## 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.
 $\begin{array}{c}{M}_{1}{V}_{1}\mathrm{=}{M}_{2}{V}_{2}\end{array}$ $\begin{array}{c}2\mathrm{×}{V}_{1}\mathrm{=}0.2\mathrm{×}100\end{array}$ $\begin{array}{c}{V}_{1}\mathrm{=}\frac{0.2\mathrm{×}100}{2}\end{array}$ $\begin{array}{c}{V}_{1}\mathrm{=}10{\mathit{cm}}^{3}\end{array}$
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.