How will you prepare 250 ml of 0.5N HCI solution and standardize it? (Sp.gravity of conc HCI-1.18 g/ml and concentration 37% w/w).
Answers
Answer:
On the bottle its written that Assay = (35-38%), also weight per ml = (~1.18g). now I need to have 9 M HCl of this HCl with this information, its not written on the bottle the exact concentration in M! so how to convert Assay to Molarity?
Given:
Sp.gravity of conc HCI-1.18 g/ml and concentration 37% w/w.
To prepare 250 ml of 0.5N HCl from 12N HCl, the volume of concentrated acid required can be calculated by using the normality equation :
N1V1 = N2V2
N1 = The normality of concentrated acid = 12 N
V1 = The volume of concentrated acid required is =?
N2 = The normality of dilute acid to be prepared is = 0.5 N
V2 =The volume of dilute acid to be prepared = 250 ml.
12 x V1 = 0.5 x 250
V1 = (0.5 × 250) / 12 = 10.4166666667 ml ≅ 10.42 ml
Therefore 10.42 ml of concentrated acid should be taken and diluted with water to make the volume 250 ml. The resulting solution will be 0.5N HCl.
Apparatus:
A measuring cylinder, A 250 ml measuring flask, A beaker, and A glass rod.
Procedure:
- Calculate the volume of 12 N HCl required for preparing 250 ml of 0.5N HCl.
- With the help of a measuring cylinder, take about 100 ml of distilled water in a 400 ml beaker. (This volume of water is slightly less than the volume of water which will be required).
- Take 10.42 ml of given concentrated HCl in a measuring cylinder. Add it slowly and carefully, by stirring with a glass rod, to the water taken in the beaker. Cool beaker under tap water in time to time.
- After all the acid has been added, transfer the solution from the beaker to a 250 ml measuring flask. Add more water so that the total volume becomes 250 ml.
- Stopper the measuring flask and shake the solution well to make it uniform. Label it as 0.5N HCl.
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