Subject 2 Purification of water

Topic 2

Purification of water

Pure water is a colorless, odorless, clear and transparent liquid. Natural water such as river water, lake water, well water, and sea water in nature contains many impurities. Insoluble impurities make it turbid, while soluble impurities may make it smell or color.

Domestic water in cities is purified and treated by waterworks. Sometimes, the jelly-like substance formed after mingji is dissolved in water can be used to absorb impurities and settle the impurities to achieve the purpose of water purification.

Precipitation, filtration, and adsorption are commonly used methods in industry, as well as for separating mixtures in chemical experiments.

If the liquid is filtered with an adsorption solid, it can not only filter out the insoluble substances, but also absorb some dissolved impurities and remove the odor. Some of the water purifiers sold on the market use activated carbon to absorb and filter impurities in the water.

After the above-mentioned precipitation, filtration, adsorption and other purification treatments, the turbid water becomes clear, but the obtained water is still not pure water. What we remove are mainly insoluble impurities in the water, and there are many dissolved impurities in the water. For example, water in some areas can easily scale kettles or water-holding utensils because there are more soluble calcium and magnesium compounds dissolved in the water in this area. When the water is heated or left for a long time, these compounds will form precipitation ( limescale). Water that contains more soluble calcium and magnesium compounds is called hard water, and water that does not contain or contains less soluble calcium and magnesium compounds is called soft water.

Hard and soft water can be tested using the above experiment. The use of hard water will bring many troubles to life and production, such as washing clothes with hard water, which wastes soap and cannot wash clothes, and it will harden clothes after a long time; high hardness of boiler water is very dangerous because of scaling inside the boiler In the end, it will not only waste fuel, but also cause local overheating of the pipeline in the boiler, which will easily cause deformation or damage of the pipeline, and may cause an explosion in severe cases.

Trying to remove calcium and magnesium compounds in hard water can soften hard water into soft water. There are many ways to soften hard water in industry and scientific experiments, and the hardness of water can also be reduced by boiling in life.

The stuffing water used in the laboratory is water with a high degree of purification, which can be prepared by steaming tap water.

You should know after finishing this topic

1.Water in nature is not pure water, and water can be purified to varying degrees through various methods.

2.Hard water contains more soluble calcium and magnesium compounds, which is prone to scale and is not easy to foam when it reacts with soap; hard water can be softened into soft water.

3.How to purify water by means of adsorption, sedimentation, filtration and steam storage.