includes apparatus, procedure and calculation formulas

1. Determination of Alkalinity in
a given water of waste water
sample

2. Apparatus:

3. Procedure:
1. Fill the burette with 0.02N Sulphuric acid and adjust it to zero.
2. Fix the burette in the stand.
3. Using a measuring cylinder exactly measure 100mL of sample and
pour it into a 250mL of conical flask.
4. Add a few drops of phenolphthalein indicator to the sample. The
solution will turn pink if the alkalinity is above pH 8.2.
5. Titrate the sample with standard 0.02 N H2SO4 solution until the pink
color disappears. Record the volume of H2SO4 solution used (V1).
6. Now add 2-3 drops of methyl orange indicator to the same solution in
the conical flask.
7. Continue titrating with 0.02 N H2SO4 solution until the sample turns
yellow or light orange. Record the volume of H2SO4 solution used
(V2).
8. Repeat the titration for concordant values.

4. Calculation formulas:
Phenolphthalein Alkalinity (P):
Calculate Phenolphthalein alkalinity in terms of mg/L as CaCO3 using the following
formula:
P (mg/L as CaCO3) = (V0-V1) x N x 50,000 / (Volume in mL of sample)
• where V1 is the volume of H2SO4 solution used for the first titration, and V0 is the
initial reading i.e 0. & N= Normality
Total Alkalinity (T):
Calculate Phenolphthalein alkalinity in terms of mg/L as CaCO3 using the following
formula:
P (mg/L as CaCO3) = (V0-V2) x N x 50,000 / (Volume in mL of sample)
• where V2 is the volume of H2SO4 solution used for the second titration, and V0 is
the initial reading i.e 0. & N= Normality

5. Concluding remarks: