How to distinguish between hard and soft water in experiments

Add soapy water, with scum for hard water, no scum for soft water.

1. Liquid soap.

2. Sodium carbonate.

With liquid soap, the more intolerable impurities appear, the greater the hardness of the water.

In the same way, with sodium carbonate, the more precipitation appears, the harder the water will be.

Hard water has calcium and magnesium ions, soft water does not.

Chemistry Virtual Experiment Distinguish between soft and hard water with soapy water.

Methods for distinguishing between hard and soft water:

Method 1: Take an equal amount of water sample from each of the two beakers. Add an equal amount of soapy water to each beaker. If there is more foam and less scuss, it is soft water. On the contrary, hard water with less foam and more scum is hard.

Method 2 can also be heated with a beaker, and it is hard water that leaves more scale on the wall of the cup. Because hard water is water that contains more soluble calcium and magnesium substances, after heating, these soluble calcium and magnesium substances are converted into insoluble substances, and it is hard water that precipitates more impurities, and the more impurities, the greater the hardness of the water.

Method 3: Take a clean, dry piece of glass. Drop an equal amount of water at different locations. After it has completely evaporated, the white residue is mostly hard water, and vice versa.

We'll be happy to answer for you.

I wish you a happy life and progress in your studies.

If you have any questions about this answer, please follow up.

If you approve of me, please be in time, if you approve of me, please click the [for satisfaction] button in time.

Friends who ask questions on their mobile phones can comment on [Satisfied] in the upper right corner of the client.

Yours is my motivation to move forward.

Remember to praise and help each other if you are satisfied.

Categories: Education Science >> Admission >> High School Entrance Examination Question Description:

Fill in the form: There is a bottle of mineral water (hard water) and a bottle of rainwater (soft water), please design an experiment to identify them separately. (in two ways).

Experimental Phenomenon Conclusion.

Method 1: Method 2:

Analysis: Method 1: Take a cup of hot water, chop the soap and put it in, the soap can be completely dissolved, and after cooling, it becomes a translucent liquid (more soap will become frozen), that is, soft water; If there is a layer of undissolved white foam on the surface of the water after cooling, it is hard water.

The more foam, the harder the water.

Method 2 can also be heated with a beaker, and it is hard water that leaves more scale on the wall of the cup. Because hard water is water containing more soluble calcium and magnesium substances, after heating, these soluble calcium and magnesium substances are converted into insoluble substances, and the precipitated impurities are hard water, and the more impurities, the greater the hardness of the water. Crack search.

Hello! Dear, I'm glad to answer for you, there are two ways to distinguish between soft water and hard water: 1. You can use soapy water to identify, soft water with more foam, and hard water with less foam So the answer is:

Take two test tubes and add a little hard water and soft water respectively, and then add 2-3 drops of soapy water to the test tube respectively to shake, the foam is more soft water, and the foam is less hard water 2, can be distinguished by the method of heating, after heating, the scale that does not generate or is not easy to generate scale is soft water, and the easy to generate scale is hard water Therefore, the answer is: take two test tubes and add a little hard water and soft water respectively, and then heat the soft water that does not produce scale or is not easy to generate scale, and the one that is easy to generate scale is hard water

Method 1: Take a cup of hot water, chop the soap and put it into it, the soap can be completely dissolved, and after cooling, it becomes a translucent liquid (the soap is more liquid and the town is frozen), that is, soft water; If there is a layer of undissolved white foam on the surface of the water after cooling, it is hard water. The more foam, the harder the water.

Method 2: You can also use a beaker to heat, leaving more limescale on the wall of the cup, and the thick is hard water. Because hard water is water containing more soluble calcium and magnesium substances, after heating, these soluble calcium and magnesium substances are converted into insoluble substances, and the precipitated impurities are hard water, and the more impurities, the greater the hardness of the water.

"Hard water"Refers to water that contains more, soluble, calcium-magnesium compounds. For example, spring water, well water, etc. in nature. "Soft water" refers to water that contains no or less soluble calcium and magnesium compounds.

For example, snow and rain in nature are soft water. Generally speaking, water with a hardness of less than 150mg l is called "soft water"; Water with a hardness greater than 150 mg l is called "hard water". 1. The substance content of water is not the same

Soft water contains no or less soluble calcium and magnesium compounds, and hard water contains more soluble calcium and magnesium compounds.

2. Soft water is not easy to produce soap scale with soap, while hard water is the opposite. Hard water does not pose a direct health hazard, but it can cause many problems in daily life, such as limescale formation on water utensils, and reduced washing efficiency of soap and detergent. This can be used to distinguish between hard water and soft water.

3. Hard water can be converted into soft water after treatment, and the softened hard water refers to the demineralized water obtained after the content of calcium salt and magnesium salt is reduced to milligram liters. The DC power supply is used as the power to selectively pass through the ion exchange membrane to obtain soft water.

4. What we usually say"Hard water"with"Soft water", which mainly refers to the content of calcium carbonate and magnesium carbonate, expressed in "milligrams of calcium carbonate liters of water" or "ppm", which is called the hardness of water.