April 2, 2017

Best way to measure alkalinity of water

Alkalinity is actually a measure of one river’s capability of neutralizing acids. This is also termed as the ‘buffering capacity’ of the river. The alkaline compounds present in the solution or water like bicarbonates, carbonates & hydroxides lower the acid state of the solution or water and remove the H+ ions. This is done usually with the combination with H+ ions in order to make newer compounds. Without the ANC (acid neutralizing capacity), any kind of acid added to the water or solution would result in an immediate & fast change in pH. In order to determine a particular river’s capability of neutralizing acidic pollution from snowmelt or rainfall, it is important to measure alkalinity. It is a very good measure of the river’s sensitivity to the acid inputs. Alkalinity comes from salts, soils, certain activities in plants, rocks and certain discharges from the industrial wasted water. The total alkalinity is estimated by first collecting a sample of the water & then measuring the right amount of acids that is needed to change that sample to the pH of 4.2.


The commonly used equipment required to do the alkalinity measurement are as follows.
• Digital Titrator

• Stir Bar

• pH-meter

• Buffers (4.01 & 7.00)

• Glass beaker (150 ml)

• Refillable electrode

• Distilled or deionized water

• Graduated cylinder (100 ml)

• Cartridge of Sulphuric acid (0.16 N)

• Magnet Stirrer

Equipment and materials required

Determination of alkalinity’s titration clearly needs these things.

• A dye or pH meter, which will change the color at pH’s end point

• A stir bar and stir plate

• Something that will hold the samples

• 0.1N acid

• Something that will accurately measure out 100 ML sample

• Something that can be used to dispense close and controlled amount of the acids


The following are the details of the procedure for alkalinity measurement

• If one is using a pH meter, then one should calibrate meter & prepare the buffers very carefully.

• If a regular buret is used to assemble it to its stand, placing it at this height will allow the drops to fall inside the flask. One should fill it with the 0.1N acid to its reference level carefully.

• The graduated cylinder should be filled to the mark of 100ml with the sample.

• Then add one stir bar to that flask. Pour the sample carefully, into that flask & place that flask on stir plate under the tip of buret. The stir plate should not be started.

• Add adequate indicator in order to allow one to see the color clearly, or one can lower pH electrode into that sample.

• Until a stable pH reading is achieved, the pH electrode has to be kept moving.

• Start the stir plate at a slow speed.

• The buret should be then operated in order to admit acid in small amounts. Wait for the reaction & for stabilization for the reading of pH meter. Note down the reading and pH of the buret.

• Keep repeating the procedure until the achievement of the desired pH reading on the meter. The desired pH is 4.5 with the solution turning pink.
Once you manage to measure the alkalinity of the water perfectly then you can easily determine the treatment procedure to make the water potable and tasty.