Hello all,
I would like to ask you about the reasons of expressing the total hardness, calcium hardness, Magnesium hardness and total alkalinity hardness in the form of CaCO3.
I have found several answers that are different to each other but most of them are not clear enough to understand the reason of the above case.
Waiting to hear from you
Regards
If I can use a comparison, turbidity in water is the reflectance of light to a sensor, and measured in nephelmetric turbidity units NTUs. Now turbidity can be caused by a combination of mineral (silts and clays) and organic particles, as well as algae or other fine biological organism, that reflect light. If you want determine effects of turbidity, you may or may not be interested in the components that cause it.
Hardness is perhaps similar. CaCO3 is used as a unit so calculations can be easily made on the level and severity of hardness effects, whether the hardness is calcium hardness, magnesium hardness, carbonate hardness or non-carbonate hardness. There are equations that can be used to add in the various types of hardness to get total hardness, but many are not interested in the details, they just want to know the severity and whether it is important to reduce its effects. Such as if you have high hardness, soap is less effective and your water heater may fail alot earlier due to the accumulation and deposits. Plastic water pipes are often used to reduce the corrosion and clogging that accumulates with hardness deposits.
So the expression as CaCO3 is to make it easy reference. But if desired, you can still separate total hardness into its elements, and you will find that magnesium hardness effects are higher than calcium hardness. But it is common to still express the elements as CaCO3 so they will be directly additive without adjusting coefficients. The simple basic testing for total hardness does not differentiate, but if important, the elements of hardness can be analyzed separately at greater expense, effort, etc.
As a researcher, it may be important to know the various sources of hardness for any area, and as such, measuring the various forms of hardness, calcium, magnesium, and whether associated with carbonate or non-carbonate components may be more important for a better understanding.
I do not know English well.
The hardness is related to the carbonate hardness corresponding to the precipitated hardness in the form of (CO 3) and (HCO 3), generally these units are used for the calculation of softening or decarbonating reagent doses or lime precipitation which lead Has a precipitation in the form of caco3
Please see the attachment for my response to your question. I hope it would help.
Thank you for all who answered my question
Yao B. your attachment was clear enough for me. regards
This is one old convention, which has some meaning when water is used for laundry och cooking. CaCO3 is used as a basis for UK hardness, french hardness and US hardness.
But also CaO is used as a basis for expression of hardness as for German hardness °dH (corresponds to CaO 10 mg/l).
The ISO standard 6059 Determination of the sum of calcium and magnesium state that the result should be given as milliequivalents per liter. A modern way of expression of the practical evaluation of water hardness.
All these are related so its easy to relate one hardness value to another.
the proximity of chemical properties, which are further reflected at the mineralogical level
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