2. About 500g of baking soda water with a concentration of 65438 0% can be poured, or vinegar can be heated and poured into a bottle, and the scale can be removed by gently shaking and washing.
3. Gently break two egg shells, put them into a bottle, then put them into a half-tea jar filled with cold water, plug them with a cork, hold them with one hand, hold the bottleneck with your thumb and other fingers, and hold the bottom of the bottle with the other hand, and rotate them up and down, left and right. For about 20 seconds, remove the cork, pour out the eggshell and rinse it twice with clear water.
4. Use 250 grams of vinegar, heat it, pour it into a thermos bottle, soak it for a few hours, and then shake it up, down and left and right, and the scale in the bottle will fall off.
5, take 200 grams of dilute hydrochloric acid in the bottle and soak it for a while, then shake it to remove the scale in the bottle.
6. Pour the cooked noodles into the bottle, shake it for a few minutes, then pour it out, and then rinse it with clear water.
7. Take some sunny leaves or pumpkin leaves and cut them into small pieces of 3 cm to 4 cm square, put them in a bottle, add a little cold water, gently shake the thermos a few times, pour them out and wash them with clear water.
scale
The scale is due to the long-term use of the kettle, and a thick layer of impurities will grow on the inner wall.
"It's fresh rain and snow, and the water contains no minerals? Soft water ". After the water is boiled, some water evaporates, and calcium sulfate (CaSO4, gypsum, insoluble, containing? Calcium sulfate of crystal water) precipitation. So it was dissolved? Calcium bicarbonate (Ca(HCO3)2) and? Magnesium bicarbonate (Mg(HCO3)2) decomposes in boiling water, releasing carbon dioxide (CO2), which becomes insoluble calcium carbonate (CaCO3) and magnesium hydroxide (? Mg(OH)2) also precipitates, sometimes forming MgCO3. This forms a scale.
The formation process of 1
Water containing more minerals such as calcium (Ca) and magnesium (Mg) salts is called "? Hard water. " Rivers, lakes, wells and springs are all hard water. Tap water is obtained from rivers, lakes or well water after precipitation, sediment removal and disinfection. Hard water, too. Fresh rain and snow, the water does not contain minerals, is "soft water." After the water is boiled, part of the water evaporates, and insoluble calcium sulfate (CaSO 4, gypsum is calcium sulfate containing crystal water) is precipitated. The original dissolved calcium bicarbonate (? Ca(HCO3)2) and magnesium bicarbonate (Mg(HCO 3) 2) are decomposed in boiling water, releasing carbon dioxide (CO 2) into insoluble calcium carbonate (CaCO 3) and magnesium hydroxide (? Mg(OH)2) will also precipitate, and sometimes MgCO 3 will be generated. This forms a scale. When washing clothes with hard water, calcium and magnesium ions in the water combine with soap to form flocculent precipitation of calcium fatty acid and magnesium fatty acid, which is the origin of "bean curd residue". Washing clothes in hard water wastes soap. Scale grows in the kettle, which is not easy to transfer heat and wastes fuel. For a family, these wastes are not serious. For the factory, the problem is big. Some large boilers used for heating and steam supply in factories emit several tons of steam per hour, which is equivalent to burning several tons of water. According to the test, one ton of river water contains about 1.6 kg of minerals; The minerals in a ton of well water are as high as 30 kilograms. How amazing is the amount of scale deposited on the inner wall of boiler by hard water when transporting dozens of tons of steam a day! Scale is formed in a large boiler, just like building a thermal insulation stone wall between the steel plate and water on the boiler wall. The steel plate of the boiler can't touch the water, and the fire in the furnace keeps burning the steel plate red. At this time, if the scale cracks, water will immediately leak to the high-temperature steel plate and evaporate quickly, resulting in the pressure in the boiler soaring and explosion. The power of boiler explosion is no less than a blockbuster! It can be seen that the harm of scale must not be taken lightly! So, in the factory, the right amount? Sodium carbonate (common name? Soda), so that calcium and magnesium salts in the water are precipitated and removed, and the water becomes soft water. Let hard water pass? Ion exchange resin can also remove minerals and get soft water? [ 1]? .
The kettle and thermos bottle at home have grown scales. How to remove it? The main components of scale are calcium carbonate and magnesium hydroxide, which can change chemically with acid. According to this truth, pour some edible citric acid or commercially available citric acid scale remover (vinegar can also be used) into the kettle and heat it on the fire, only to see dense small bubbles released on the scale, and the scale will dissolve quickly. It is no problem to remove the scale from the thermos bottle like this.
2 hard scale and soft scale
According to the formation reason and state of scale, scale can be roughly divided into hard scale and soft scale. When water contains impurities such as carbonate colloid, bacteria and organic matter, carbonate is similar to sand in cement mortar, while colloid, bacteria and organic matter are equivalent to cement in cement mortar. Viscous substances such as colloid, bacteria and organic matter in water interact with carbonate to form hard scale attached to the container (or pipeline surface) when boiling at high temperature. Once the viscous substances such as colloid, bacteria and organic matter are removed (for example, by ultrafiltration), even if the concentration of calcium, magnesium ions and carbonate ions in water is high, it will become white and loose carbonate soft scale, which is easy to remove and will not produce hard scale.
Composition: The composition of scale is generally complex and consists of many compounds. The chemical composition of scale is generally expressed by mass fraction.
Classification: Scale is divided into calcium-magnesium scale, silicon scale, phosphate scale, iron scale and copper scale according to its main chemical components.