Relationship Table of Alkalinity:
Result of titration |
Hydroxide (OH) |
Carbonate (CO3) |
Bicarbonate (HCO3) |
p = 0 |
Nil |
Nil |
T |
p > t/2 |
2p - T |
2(T - p) |
Nil |
p = t/2 |
Nil |
2p |
Nil |
p < t/2 |
Nil |
2p |
T - 2p |
p = T |
p |
Nil |
Nil |
Where P= phenolphthalein alkalinity, T= Total alkalinity
Apparatus:
Satnd, buretle, funnel, conical flask, beaker etc.
Chemicals:
Phenolphthalein indicator solution, brome cresel green, methyle red solution, standard solution ( H2SO4) having normality 0.02
Procedure:
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Take 50 ml of water sample in a flask. Add six drops of phenophthalein indicator in the sample (water), note the initial reading of the buretle containing H2SO4 (N=0.02)
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Start the titration till the color changes and note the reading of the buretle, Calculate the phenolphthalein alkalinity using the formula alkalinity = (final reading - initial reading) X 100/50
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Now add six drops of brome cresol green in the methyle solution which turns the color to greenish one. note the initial reading of the buretle and start the titration till the color changes to gray and note the final reading.
-
Calculate total alkalinity by using the formula,
Total alkalinity = (final reading - initial reading) x 100/50
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