How can I quickly detect the amount of calcium ions in water? No chemical methods are required and n

Hehe, well, it's rare to see such a high score.

This question is very interesting, if only ions are measured, the above methods have many limitations, for example, liquid chromatography is indeed suitable for liquid detection, but the commonly used ultraviolet detector is not high, and calcium ions have no ultraviolet absorption, and the fluorescence detector with higher sensitivity in high-performance liquid phase needs to coordinate calcium ions, which is not good. Not to mention nuclear magnetic resonance, I have never heard of liquid nuclear magnetic resonance (NMR) with nuclear magnetic calcium spectroscopy, as for doing hydrogen spectroscopy in water, does it make sense?

You can use liquid chromatography, nuclear magnetic resonance, etc.

It's fast and accurate, and it can be measured in a few seconds.

In fact, the chemical method is the simplest, so why do you have to do high-tech things.

Expensive and cumbersome.

The water is boiled dry, and the remaining amount of calcium ions can be calculated as the molecular weight of calcium carbonate.

Carbonic acid is added to the water, then the water is evaporated, and if a white solid appears, it contains calcium ions.

Hardness. The total hardness of water refers to the total concentration of calcium and magnesium ions in the water. These include carbonates.

Hardness (that is, calcium and magnesium ions that can be precipitated in the form of carbonate by heating, so it is also called temporary hardness and non-carbonate hardness (that is, the part of calcium and magnesium ions that cannot be precipitated after heating, also known as permanent hardness).

The sum of carbonate hardness and non-lead carbonate hardness is called total hardness; The water is just the right amount of calcium in it.

The amount is called calcium hardness; The amount of magnesium ions in water is called magnesium hardness; When the total hardness of water is less than the total alkalinity, the difference between the two is called negative hardness.

So it can be considered a concept.

Water Quality Objectives.

The unit of hardness is milligram liters, which converts calcium ions into calcium oxide.

Later, the mass is calculated, which is equivalent to the mass containing CAO per liter of water.

The book of calcium is relative to atomic mass.

40, oxygen 16, adds up to 54

Each liter of water ca2- is considered to be calcium oxide, and the mass is 54*, which is the water hardness.

In addition, it is expressed by the mass of CaCO3, and the relative molecular mass of calcium carbonate is replaced by 54 in the above equation.

100 is sufficient.

I don't know what kind of macro method you use.

First, the specimen is prepared into a solution.

One is to cooperate with the titration method, use EDTA standard solution to titrate calcium ions in the solution, and use calcium red as an indicator, pH=12, to measure calcium ions.

One is indirect redox titration, first precipitate calcium ions with ammonium oxalate, filter after aging, dissolve calcium oxalate with sulfuric acid, and then titrate oxalate in the solution with potassium permanganate standard solution, and calculate the content of calcium ions according to the amount of potassium permanganate consumed.

For example, the potentiometric method uses a calcium electrode to measure the calcium content.

For example, spectrophotometry uses chromogenic reagents to develop color with calcium ions, and then uses the law of light absorption to find the concentration of calcium ions according to the absorbance proportional to the concentration.

Remember to do it by titration, if you want to know how, tomorrow.

If limited to high school chemistry, the determination of calcium ions can be measured by the flame color reaction, which is brick-red.

If titration is used, it can be titrated with oxalic acid - calcium oxalate is insoluble.

However, it is worth noting that the phenomenon of precipitation caused by the reaction of calcium ions and carbonate often cannot directly determine that calcium ions are involved in the reaction, because magnesium ions and barium ions also have the same phenomenon. Judging calcium ions generally appears in inorganic inference problems, and is often mixed with other examples for us to judge. Therefore, it can be screened out by carbonate overtitration first, and then other judgments can be made.

There are two main systems: the volume method and the instrument method; There are three main types of volumetric methods: gravimetric method, complexation titration method, and redox method.

soluble calcium salt) with sodium carbonate, and the solution should be neutral or alkaline. (If there are calcium ions, there will be white calcium carbonate precipitation) (Insoluble calcium salt) Add hydrochloric acid to make the solution acidic, then the precipitate will slowly dissolve. Sodium carbonate is then used to make the solution neutral or alkaline.

If there are calcium ions, there will be white calcium carbonate precipitates).

It is most convenient to use the colorimetric method, and the pond willow ion detection box produces the result in 5 minutes, with an accuracy rate of more than 99%.

Hardness is expressed by considering both Ca2+ and Mg2+ in water as Ca2+ and converting it into the mass of CaO. Usually 1L of water containing 10mgCaO is called 1 degree, and 1L of water containing 20mgCaO is 2 degrees; And so on.

Above 8 degrees is hard water, and below 8 degrees is soft water.

1L of water sample contains: Ca2+: i.e., 100mg, Mg2+: i.e., 48mg

The converted into CAO is: 100 56 40 +48 56 24 = 252mg

Then the hardness of the water sample is 252mg 10=8 degrees, which is hard water.

If it is a liquid sample, ammonium oxalate solution is added, and turbidity occurs, that is, calcium ions are contained.

Soluble oxalate or oxalic acid can be used to test for calcium.

Principle: The calcium oxalate precipitate generated by C2O42- and Ca2+ is very insoluble in water, and it is also difficult to dissolve in dilute strong acids (such as one mole per liter of hydrochloric acid).The similar barium oxalate, magnesium oxalate, and strontium oxalate are soluble in dilute strong acids, which is the special feature of calcium oxalate, so when identifying common ions, if soluble oxalate or oxalic acid solution is added, the resulting white precipitate is insoluble in dilute strong acid, then it means that the test solution contains calcium ions.

Note that calcium oxalate is soluble in concentrated hydrochloric acid!

Transportable soluble oxalate or oxalic acid can be used to test for calcium orange ions.

Principle: The calcium oxalate precipitate generated by C2O42- and Ca2+ is very insoluble in water, and it is also difficult to dissolve in dilute strong acids.

such as one mole per liter of hydrochloric acid).The similar barium oxalate, magnesium oxalate, and strontium oxalate are soluble in dilute strong acids, which is the special feature of calcium oxalate, so when guessing common ions, if soluble oxalate or oxalic acid solution is added, the resulting white precipitate is insoluble in dilute strong acid, then it means that the test solution contains calcium ions.

Note that calcium oxalate is soluble in concentrated hydrochloric acid!