Alkaline ionised water commonly known as Alkaline water has high pH value. Notably, pH is a measure of the acid-base balance of water. Significantly, Alkalinity is one of the most important things measured in the chemistry of water.
Usually, the pH of natural water ranges between 6.5 and 8.5, and it is controlled by the carbon dioxide-bicarbonate-carbonate equilibrium system. Alkalinity is present in water as dissolved minerals like calcium and magnesium.
The alkali metals are found in earth’s crust and it is everywhere in nature. Alkalinity is the ability of a liquid or substance to resist a change in pH, or the capacity of water to buffer against an acid.
What is Alkalinity?
Alkalinity indicates how much acid a solution can absorb without changing the pH. It is the buffering capacity of a solution (water). Therefore, solutions with low alkalinity have a lower buffering capacity, and change pH rather quickly when something acidic is added.
On the contrary, high alkalinity of water samples have a higher buffering capacity and are less affected when something acidic is added. It becomes necessary to add a lot more acid in order to obtain the same pH change as in a low alkalinity of water sample.
What Causes Alkalinity?
Alkalinity of water differs according to the geographical location. The soil and minerals of the particular geographical location influences the amount of alkalinity in natural water sources. Primarily, the areas where limestone are present predominantly have higher alkalinity in water.
Alkalinity Measurement
Alkalinity is essential in several industries for water treatment. It is highly essential to ensure a proper alkalinity test from a trusted water testing laboratory.
The accurate monitoring of alkalinity will save materials, money and time of users. When measuring alkalinity of water, the results are displayed as ppm of calcium carbonate (CaCO3). Hydroxide (OH–) ions, bicarbonate (HCO3–) ions, and carbonate (CO32-) ions all contribute to water alkalinity.
Whether it is drinking water or wastewater treatment processes alkalinity is a parameter that is closely monitored. Optimal alkalinity can streamline treatment, and cut down on the time and materials spent. Improper alkalinity can cause issues such as slowed treatment reactions, additional materials needed, stalled treatment, end product imperfections, and environmental implications.
How to determine alkalinity in water
1.Take a 20 ml sample solution in a conical flask and add 2-3 drops of phenolpathalein indicator.
2.Titrate this against HCl solution until the solution becomes colourless, note the readings.
3.Add 2-3 drops of methyl orange indicator and titrate it again.
4.Stop when you see red colour and note down the reading.
What is Total Alkalinity?
Total alkalinity measures the level of alkaline in water, it is the measurement of the concentration of all alkaline substances that dissolves in water.
Total alkalinity is measured by measuring the amount of acid (e.g., sulfuric acid) needed to bring the sample to a pH of 4.2. At this pH all the alkaline compounds in the sample are “used up.” The result is reported as milligrams per liter of calcium carbonate (mg/L CaCO3).
It can be appositely tested in a laboratory. For instance, in swimming pools water bicarbonate alkalinity should be in between 80 ppm and 120 ppm. If the total alkalinity is within this range then it will prevent rapid pH changes and will stabilize the pH level in the water.
If the total alkalinity is lower than required level the pool water could turn green and it will cause irritation in eyes of people and rigid stains on walls of the pool.
Types of Alkalinity:
Two types of Alkalinity present in water,
- P-Alkalinity also called Phenolphthalein Alkalinity because Phenolphthalein indicator used for analysis
- M-Alkalinity also called Methyl orange Alkalinity because Methyl orange indicator used for analysis
Water Alkalinity test in Laboratories
Our labs conduct water alkalinity tests to measure the concentration of alkaline in water. It is one of the top 5 laboratories in India situated in multiple locations to solve all the water testing requirements.
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