📚 Some Uses of Group 2 Compounds | 第2族化合物的一些用途
Group 2 elements, known as the alkaline earth metals, form a wide range of compounds with many practical applications. These applications depend on their chemical properties, such as basicity, solubility, and thermal stability. This article reviews some important uses of Group 2 compounds in agriculture, medicine, construction, and industry.
第2族元素又称碱土金属，能形成许多具有实际用途的化合物。这些用途取决于它们的化学性质，如碱性、溶解度和热稳定性。本文介绍一些第2族化合物在农业、医学、建筑和工业中的重要用途。
1. Calcium Oxide (Quicklime) | 氧化钙（生石灰）
Calcium oxide, CaO, is a white alkaline solid produced by heating limestone. It is commonly called quicklime.
氧化钙（CaO）是一种白色碱性固体，通过加热石灰石制得，俗称生石灰。
Use as a drying agent: Quicklime is an effective desiccant because it reacts readily with water. It is used to remove water from solvents and gases.
用作干燥剂：生石灰是一种高效干燥剂，因为它能迅速与水反应，常用于去除溶剂和气体中的水分。
CaO(s) + H₂O(l) → Ca(OH)₂(s)
Use in manufacturing: Quicklime is the starting material for making slaked lime, mortar, and many industrial chemicals.
用于制造：生石灰是制造熟石灰、灰浆和许多工业化学品的原料。
2. Calcium Hydroxide (Slaked Lime) | 氢氧化钙（熟石灰）
Calcium hydroxide, Ca(OH)₂, is a sparingly soluble base. A saturated solution is called limewater.
氢氧化钙（Ca(OH)₂）是一种微溶的碱，其饱和溶液称为石灰水。
Neutralising acidic soils: Farmers add slaked lime to acidic soils to raise pH and improve crop growth.
中和酸性土壤：农民向酸性土壤中加入熟石灰以提高 pH 值，促进作物生长。
Testing for carbon dioxide: Limewater turns milky when CO₂ is bubbled through it, forming insoluble calcium carbonate.
检验二氧化碳：当 CO₂ 通入石灰水时，石灰水变浑浊，因为生成了不溶的碳酸钙。
Ca(OH)₂(aq) + CO₂(g) → CaCO₃(s) + H₂O(l)
Other uses: Slaked lime is used in mortar, whitewash, and in making bleaching powder.
其他用途：熟石灰用于灰浆、粉刷以及制造漂白粉。
3. Calcium Carbonate (Limestone) | 碳酸钙（石灰石）
Calcium carbonate, CaCO₃, is found naturally as limestone, chalk, and marble. It is a major industrial raw material.
碳酸钙（CaCO₃）天然存在于石灰石、白垩和大理石中，是一种重要的工业原料。
Building material: Crushed limestone is used directly in road construction, while cut limestone and marble are used for buildings and monuments.
建筑材料：碎石直接用于筑路，切割后的石灰石和大理石用于建筑和纪念碑。
Manufacturing: Limestone is heated to form quicklime and is also used to make cement, glass, and iron.
工业生产：石灰石加热生成生石灰，还用于制造水泥、玻璃和铁。
CaCO₃(s) → CaO(s) + CO₂(g) (Δ)
Medicine: Calcium carbonate is used in antacids to neutralise excess stomach acid.
医药：碳酸钙用于抗酸药，中和胃中过多的酸。
Agriculture: Finely ground limestone is spread on fields to reduce soil acidity, especially in areas with heavy rainfall.
农业：磨碎的石灰石撒在田里可降低土壤酸性，尤其在降雨多的地区。
4. Magnesium Hydroxide | 氢氧化镁
Magnesium hydroxide, Mg(OH)₂, is a white solid with low solubility in water. It forms a suspension called milk of magnesia.
氢氧化镁（Mg(OH)₂）是一种白色固体，在水中的溶解度较低，其悬浮液称为镁乳。
Antacid: Magnesium hydroxide is used to relieve indigestion and heartburn. It is a mild base that reacts with hydrochloric acid in the stomach.
抗酸剂：氢氧化镁用于缓解消化不良和胃灼热。它是一种弱碱，能与胃中的盐酸反应。
Mg(OH)₂(s) + 2HCl(aq) → MgCl₂(aq) + 2H₂O(l)
Other uses: It is also used in sewage treatment to neutralise acidic waste water and as a flame retardant.
其他用途：它还可用于污水处理，中和酸性废水，并用作阻燃剂。
5. Magnesium Carbonate | 碳酸镁
Magnesium carbonate, MgCO₃, occurs naturally as magnesite. It is a white solid and an important industrial compound.
碳酸镁（MgCO₃）以菱镁矿形式天然存在，是一种白色固体和重要的工业化合物。
Sports chalk: Gymnasts and rock climbers rub magnesium carbonate on their hands to reduce sweating and improve grip.
运动防滑粉：体操运动员和攀岩者把碳酸镁涂在手上以减少出汗、增加抓握力。
Antacid: Like magnesium hydroxide, magnesium carbonate is used in indigestion remedies because it neutralises stomach acid.
抗酸剂：与氢氧化镁类似，碳酸镁也用于治疗消化不良，因为它能中和胃酸。
MgCO₃(s) + 2HCl(aq) → MgCl₂(aq) + H₂O(l) + CO₂(g)
Flame retardant: When heated, MgCO₃ decomposes to give MgO and CO₂; the CO₂ helps to smother flames.
阻燃剂：加热时 MgCO₃ 分解生成 MgO 和 CO₂，CO₂ 有助于隔绝空气灭火。
6. Barium Sulfate | 硫酸钡
Barium sulfate, BaSO₄, is famously insoluble in water and dilute acids. This property makes it safe for medical use despite the toxicity of barium compounds.
硫酸钡（BaSO₄）以不溶于水和稀酸著称。尽管钡化合物有毒，但这一性质使其在医学上可安全使用。
Barium meal (medical imaging): Patients swallow a suspension of BaSO₄ before an X-ray of the stomach or intestines. BaSO₄ absorbs X-rays, so the digestive tract appears clearly.
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