定义Definition
硫酸是化学式为 H₂SO₄ 的强二元含氧酸，纯品为无色油状液体。浓硫酸具有吸水性、脱水性和强氧化性，稀硫酸具有酸的通性。它是产量最大的化工产品，常被称为“化学工业之母”。
Sulfuric acid, H₂SO₄, is a strong diprotic oxyacid; the pure substance is a colourless, oily liquid. Concentrated acid is hygroscopic, dehydrating and strongly oxidising, while dilute acid shows ordinary acid behaviour. It is the chemical made in the largest tonnage and is often called the mother of the chemical industry.
结构与性质Structure and properties
硫原子位于四面体中心，与两个羟基和两个氧相连，S=O 键长约 142 pm，S–OH 约 157 pm。第一步电离完全（pKa₁ ≈ −3），第二步 pKa₂ = 1.99。浓硫酸与水混合时大量放热（约 −880 kJ/kg），稀释时必须把酸缓慢加入水中，绝不能把水倒入浓硫酸。
Sulfur sits at the centre of a tetrahedron bonded to two hydroxyl groups and two oxygens; S=O is about 142 pm and S–OH about 157 pm. The first ionisation is complete (pKa₁ ≈ −3) and the second has pKa₂ = 1.99. Mixing with water releases a great deal of heat (about −880 kJ/kg), so always add acid slowly to water, never water to concentrated acid.
历史与生产History and production
中世纪炼金术士干馏绿矾（FeSO₄·7H₂O）得到硫酸，称为“矾油”。1746 年罗巴克发明铅室法，实现大规模生产。1831 年菲利普斯获得接触法专利，以 V₂O₅ 为催化剂将 SO₂ 氧化为 SO₃，再用 98.3% 浓硫酸吸收，这是今天的主要工艺。全球年产量超过 2.5 亿吨。
Medieval alchemists distilled green vitriol (FeSO₄·7H₂O) to obtain the acid, called oil of vitriol. Roebuck's lead-chamber process of 1746 allowed large-scale production. Phillips patented the contact process in 1831: SO₂ is oxidised to SO₃ over V₂O₅ and absorbed in 98.3% acid, the main method today. World output exceeds 250 million tonnes a year.
用途与安全Uses and safety
约一半以上的硫酸用于生产磷肥和硫酸铵，其余用于金属冶炼、石油精制、铅酸蓄电池电解液、制药和染料。浓硫酸能使皮肤和有机物迅速脱水炭化，溅到皮肤上应立即用大量水冲洗。
More than half goes into phosphate fertilisers and ammonium sulfate; the rest serves metallurgy, petroleum refining, lead–acid battery electrolyte, pharmaceuticals and dyes. Concentrated acid rapidly dehydrates and chars skin and organic matter; flush any splash immediately with plenty of water.
反应Reactions
接触法：用 98.3% 浓硫酸吸收 SO₃，避免形成酸雾。
Contact process: SO₃ is absorbed in 98.3% acid to avoid forming acid mist.
浓硫酸的强氧化性
Oxidising power of the concentrated acid
使蔗糖脱水炭化（“黑面包”实验）
Dehydration of sucrose to carbon (the 'black snake' demonstration)
生成不溶于酸的白色沉淀，检验 SO₄²⁻
An acid-insoluble white precipitate, a test for sulfate
化学性质Chemical properties
吸水性：可作干燥剂，干燥 H₂、O₂、CO₂、Cl₂ 等，但不能干燥 NH₃、H₂S。
Hygroscopic: it dries H₂, O₂, CO₂ and Cl₂, but not NH₃ or H₂S.
脱水性：按 2:1 夺取有机物中的 H、O，使纸张、木材炭化。
Dehydrating: it removes H and O in a 2:1 ratio from organic matter, charring paper and wood.
冷的浓硫酸使铁、铝钝化，可用铁罐储运。
Cold concentrated acid passivates iron and aluminium, so it can be stored in steel tanks.
年表Timeline
- 约 13 世纪
炼金术士干馏绿矾制得硫酸
Alchemists distil green vitriol to make the acid
- 1746
罗巴克发明铅室法
Roebuck invents the lead-chamber process
- 1831
菲利普斯获接触法专利
Phillips patents the contact process
- 1915
巴斯夫开始使用 V₂O₅ 催化剂
BASF introduces the V₂O₅ catalyst