Total Hardness of Water: Understanding its Importance and Calculation
Water hardness is a critical parameter in various industries, including water treatment, chemical processing, and power generation. The total hardness of water refers to the concentration of calcium and magnesium ions, which can cause scaling, corrosion, and other problems. In this article, we'll delve into the importance of total hardness, and its calculation, and provide a handy calculator to simplify the process.
Why is Total Hardness Important?
Total hardness affects various aspects of water usage:
- Scaling and Corrosion: High levels of calcium and magnesium ions can cause scaling in pipes, boilers, and equipment, leading to reduced efficiency and increased maintenance costs.
- Water Treatment: It influences the effectiveness of water treatment processes, such as reverse osmosis and ion exchange.
- Industrial Processes: It can impact the quality of products in industries like textiles, paper, and food processing.
Total Hardness Testing Method :
Here's the science behind the method: it's based on a reaction between calcium and magnesium salts with a special compound called ethylenediaminetetraacetate (EDTA). To help us see when the reaction is complete, we use a clever indicator called Erichrome Black T. This indicator changes color when the reaction is finished, making it easy to determine the exact amount of calcium and magnesium present.
Reagents:
Erichrome black T solution:
– dissolve 0.5g of Erichrome black T in 100ml of triethanolamine
Buffer solution:
To prepare the reagent, start by dissolving 40g of borax in approximately 800ml of distilled water. In a separate solution, combine 10g of NaOH, 10g of sodium potassium tartrate, and 5g of sodium sulphide in 100ml of distilled water. Once both solutions are prepared, mix them together and allow the mixture to cool. Finally, dilute the solution to a total volume of 1000ml with distilled water. Note that the reagent has a limited shelf life and should not be used more than one month after preparation.
Standard EDTA solution:
– (0.02N) In 1liter round bottom flask dissolve 3.72g of disodium ethylenediaminetetraacetate dihydrate in water and fill it up to the mark.
Procedure:
Now it's time to measure out 50ml of your sample into a 250ml conical flask. Next, add 2-3 drops of indicator solution and give it a good mix. Then, add 0.5ml of buffer solution and mix again. You're almost ready to titrate! Start adding the EDTA solution while continuously mixing until you see the color change from red to blue. Keep an eye out for the endpoint - as you get close, you'll notice some blue coloration, but the solution will still have a reddish tinge. Don't worry, that's normal! Just keep going until the red color disappears completely.
Calculation:
Total hardness (as CaCO3), mg/l= 1000×V1/V2
WhereV1= volume in ml of Std EDTA sol consumed, andV2= volume in ml of the sample taken for the test
Total Hardness Calculator:
By entering the values obtained from the experiment the below output value gives the calculated total hardness of water
Total hardness is calculated by adding the concentrations of calcium and magnesium ions, expressed in milligrams per liter (mg/L) as calcium carbonate (CaCO3).
The formula is:
- Total Hardness (mg/L as CaCO3) = Calcium (mg/L as CaCO3) + Magnesium (mg/L as CaCO3).