Preparation of solutions

1. By
Mrs. Shinde Pooja Nilkanth

2. Oxalic acid
Preparation of 0.1 N oxalic acid
Oxalic acid is primary standard substance so
does not requires standardization.
Molecular weight 126
Normality = Molecular weight/acidity
N = 126/2 = 63
63gm per litre of oxalic acid for 1N
6.3gm per litre of oxalic acid for 0.1N

3. Take 1000ml of volumetric flask and transfer
The accurate amount of 6.3gm of oxalic acid,
dissolve in 100ml distilled water and make
final volume up to 1000ml by using distilled
water. Normality of the prepared oxalic acid
solution will be 0.1N
Sodium hydroxide
Preparation of 0.1 N sodium hydroxide
Sodium hydroxide is secondary standard
substance so it requires standardization.
Molecular weight 40
Normality = Molecular weight/basicity
N = 40/1 = 40
40gm per litre of oxalic acid for 1N
4 gm per litre of oxalic acid for 0.1N

4. Take 1000ml of volumetric flask and transfer
The accurate amount of 4gm of sodium
hydroxide, dissolve in 100ml distilled water
and make final volume up to 1000ml by using
distilled water. Normality of the prepared
sodium hydroxide solution will be 0.1N
Standardization of NaOH
Transfer 10ml prepared NaOH to a conical
flask and add two drops of methyl orange
indicator to this solution.
Take standardized HCl solution in burette and
add gradually drop wise to conical flask near
the end point colour of the solution turns to red
from yellow – orange.

5. Preparation of 0.1 M sodium thiosulphate
sodium thiosulphate is secondary standard
substance so requires standardization.
Molecular weight
Molarity =
gm per litre of oxalic acid for 1N
gm per litre of oxalic acid for 0.1N

6. Preparation of sodium thiosulphate
Dissolve about 24.8gm of sodium thiosulphate in
100ml distilled water ,add about 0.2 gm of
sodium carbonate as preservative. Make up
volume 1000ml with distilled water.
Standardization of prepared sodium thiosulphate
solution
1. Weigh 0.21gm of potassium dichromate and
dissolve in 100ml distilled water add 3gm of
potassium iodide, 2gm sodium bicarbonate
and 5ml concentrated HCl and keep this
iodine flask in dark for 10 minutes.
2. Take prepared solution and titrate liberated
iodine with prepared sodium thiosulphate
solution until the colour changes to yellowish
green.
3. Add 3ml starch indicator and carry out the
titration until blue colour disappears.

7. Hydrochloric acid
Preparation of 0.1 N hydrochloric acid
Hydrochloric acid is secondary standard substance
so it requires standardization.
Concentrated HCl has approximately 11.5N
strength
N1V1 = N2V2
N1 = 11.5
V1 = ?
N2 = 0.1
V2 = 1000 ml
11.5 × V1 = 0.1 × 1000
V1 = 8.70 ml

8. Take 200 – 300 ml distilled water into a 1000ml
volumetric flask and add 8.7ml concentrated
HCl drop wise in volumetric flask and finally
makeup volume up to 1000ml by using distilled
water.
Standardization
Transfer 10 ml prepared hydrochloric acid
solution in to conical flask , add two drops of
methyl orange indicator .
Take sodium carbonate in burette and add with
continuous stirring in to conical flask continue
the addition until colour turns to orange from
red and finally orange to yellow at the end
point.

9. Sulphuric acid
Preparation of 0.1 N sulphuric acid
Sulphuric acid is secondary standard substance
requires standardization.
Concentrated sulphuric acid has approximately
36.5N strength.
N1V1 = N2V2
N1 = 36.5
V1 = ?
N2 = 0.1
V2 = 1000ml
36.5 × V1 = 0.1 × 1000
V1 = 2.74

10. Take 200 – 300 ml of distilled water in to
1000ml volumetric flask and slowly add 2.74ml
concentrated sulphuric acid drop wise in
volumetric flask make up the volume up to
1000ml by distilled water.
Standardization
Transfer 10ml prepared sulphuric acid solution
in to conical flask then add one or two drops of
methyl orange indicator to this solution.
Take sodium carbonate in burette and add
gradually with continuous stirring, continue the
addition until colour of solution turns to orange
from red and finally yellow at the end point.

11. Potassium permangmate
Preparation of 0.1 N KMnO4

12. Dissolve 3.16 gm of KMnO4 in 1000ml distilled
water filter and cool.
Standardization
1. Pipette out 25ml prepared 0.1 N oxalic acid
solution, add 5ml concentrated sulphuric acid
along the side of the flask stir and warm up to 70
degree Celsius.
2. Titrate the warmed solution against the
potassium permangmate solution from burette till
pink colour persists for30 seconds.

13. Cerric ammonium sulphate
Preparation of cerric ammonium sulphate
Dissolve 66gm of cerric ammonium sulphate
in 500ml distilled water containing 30ml
concentrated sulphuric acid with gentle
heating. Cool the prepared solution filter and
finally make up the volume up to 1000ml by
distilled water.
Standardization
1. Weigh accurately 0.2gm of arsenic
trioxide and transfer to 500ml conical flask.
2. Wash inner walls with 25ml sodium
hydroxide(8%w/v) stir to dissolve add
100ml water and mix.
3. Add 30ml dilute sulphuric acid(10%w/v)
0.15ml of osmic acid
solution(0.1%)0.1ml of ferroin sulphate
solution.

14. Titrate the above mixture with cerric
ammonium sulphate solution until the
pink colour is changed to pale blue.