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Things You'll Need
Instructions
Collect a sample of the water for analysis. Collect the water sample in a bottle and return to the laboratory bench. You will need 5 ml for each test. However, if the concentration is less than 100 ppm, you will need 15 ml of sample.
Check the contents of the test kit to make sure you have all the supplies to perform the test. Each kit should contain one bottle of phenolphthalein indicator with dropper, one bottle of bromophenol indicator with dropper, one bottle of acid titrant, two calibrated vessels and one calibrated syringe with tip.
Perform the phenolphthalein test for alkalinity. Rinse the small plastic test vessel with the water sample and then fill to the 5 ml mark with the sample. Put the cap back on the vessel.
Add one drop of phenolphthalein indicator to the sample vessel. The solution should turn pink or red. If the sample remains colorless, record the alkalinity as zero and test for total alkalinity.
Push the plunger of the calibrated syringe to the end and place the tip in the bottle of HI 3811-0 titrant. Withdraw the plunger until the syringe is full and the plunger is at the 0 ml mark.
Insert the syringe tip into the top of the cap of the sample vessel and add the contents of the syringe dropwise while swirling the cup in small circles. The swirling aids in mixing the contents of the sample vessel between drops.
Continue adding titrant until the solution turns colorless. As you near the endpoint of the titration, the solution will become colorless but then return to pink or red after a few seconds. Continue the titration until the solution turns colorless and remains colorless.
Read the volume of titrant solution used and multiply the volume by 300 to calculate the ppm CaCO3 in the sample.
Perform the test for total alkalinity on the sample. The procedure is the same as the determination of phenolphthalein alkalinity except that you use bromophenol blue as the indicator.
Use 5 ml of sample in the plastic vessel. Perform the steps for this analysis the same as you did for the phenolphthalein titration. If the solution turns yellow when you add the bromophenol blue indicator, the sample is acidic and the alkalinity is zero.
Calculate the ppm CaCO3 by multiplying the volume of titrant used by 300. If the concentration of alkalinity is below 100 ppm, then perform more sensitive titration using 15 ml of water in the larger plastic vessel. Repeat the test for both phenolphthalein and bromophenol blue indicator as before.
Obtain the concentration of alkalinity using the 15 ml sample by multiplying the volume of titrant used by 100. This calculation will yield the ppm CaCO3.