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三、关于水和土壤溶液的酸度与浓度北方地区水土多呈碱性。尤其是北京属石灰岩地区,石灰岩在雨水的作用下会形成可溶于水的碳酸氢钙。北京的自来水多为地下水,因而水中碳酸氢钙含量很多。这种含有大量溶质的水称为硬水,其中含碳酸氢钙的叫暂时硬水,含硫酸钙、硫酸镁、硫酸锰等硫酸盐的叫永久硬水。暂时硬水加热后二氧化碳蒸发,部分碳酸钙会沉淀下来(即水壶中的水垢),但仍有一部
Third, on the acidity and concentration of water and soil solution in the northern region mostly alkaline soil and water. Especially in limestone in Beijing, limestone forms a water-soluble calcium bicarbonate under rainwater. Beijing’s tap water is mostly groundwater, so the content of calcium bicarbonate in water is very high. This type of water, which contains a large amount of solute, is called hard water. Hard carbonated water containing calcium bicarbonate called permanent hard water contains sulfate, calcium sulfate, magnesium sulfate and manganese sulfate. After the temporary hard water heating carbon dioxide evaporation, part of the calcium carbonate will precipitate down (that is, the scale in the kettle), but there is still a