Preparation and Standardization of 0.5 Normal
Hydrochloric Acid Solution
Preparation of 0.5 N Hydrochloric Acid Solution
¨ For
the preparation of 0.5 N Hydrochloric Acid (HCl), take 42 ml of HCl and dilute
it with carbon-dioxide free water up to 1000 ml.
¨ Gram
equivalent weight of HCl = 1+35.5= 36.5
¨ Mass
in gram
= Normality
x gram equivalent weight x required volume
1000
¨ Mass
in gram= 0.5 x 36.5x 1000 = 18.25
gram
1000
¨ Now
convert mass into volume by using following formula
¨ Density
= Mass
Volume
Re
arrange the formula, Volume = Mass
density
Density
of HCl = 1.19
Volume =
18.25/ 1.19 = 15.34 ml
¨ The
above said volume is for 100% pure HCl, however the available HCl is 37% pure,
hence the volume required will become
¨ 15.34 x 100 = 41.46 (42) ml
37
¨ Hence
to prepare 1 liter, 1 normal solution of HCl we will take 42 ml of HCl in
carbon-dioxide free 1 liter water.
Standardization
¨ Accurately
weight 0.5 gram (500mg)of anhydrous Sodium carbonate and dried it as per the
instructions given on the label.
¨ However
if no such instructions are available then dried the anhydrous sodium carbonate
for 1 hour at 270◦C.
¨ Dissolve
it in 100 ml of carbon-dioxide free water.
¨ Add
0.1 ml of methyl orange solution.
¨ Titrate
with 0.5 normal HCl solution with constant stirring until the solution becomes
reddish yellow.
¨ Boil
it for 2 minutes and continue the titration with constant stirring until the
reddish yellow color restored.
¨ Each
1 ml of 0.5 normal hydrochloric acid is equivalent to 26.50 mg of odium
carbonate anhydrous.
¨ Normality
= weight of anhydrous sodium
carbonate taken
26.50x ml of 0.5 normal HCl used
¨ Normality=
weight of anhydrous sodium carbonate taken
26.50 x ml of 0.5 normal HCl
used
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