📚 The Reactions of Metals with Acids | 金属与酸的反应
When a reactive metal is added to an acid, bubbles of gas appear, the mixture may get warmer, and the metal gradually disappears. This is a classic KS3 chemistry reaction that helps us understand acids, salts and the reactivity of metals.
把活泼金属加入酸中，会产生气泡，混合物可能变热，金属逐渐消失。这是 KS3 化学中经典的反应，帮助我们理解酸、盐和金属的活动性。
1. Metals and Acids: A First Look | 金属与酸：初识反应
If you place a piece of magnesium ribbon into dilute hydrochloric acid, you will see rapid fizzing. The fizzing is caused by a gas being produced. At the same time, the magnesium ribbon becomes smaller and eventually disappears if enough acid is present.
如果把一段镁条放入稀盐酸中，你会看到快速冒泡。这些气泡是由生成的气体引起的。同时，镁条逐渐变小，如果酸足够，最终会完全消失。
This is not dissolving in the way sugar dissolves in water. A new substance is formed. The magnesium atoms react with the acid to make a salt and hydrogen gas.
这不是像糖溶于水那样的溶解。生成了新的物质。镁原子与酸反应，生成一种盐和氢气。
2. The General Word Equation | 一般文字方程式
All reactions between reactive metals and dilute acids follow the same pattern. The general word equation is:
所有活泼金属与稀酸的反应都遵循相同模式。一般文字方程式为：
metal + acid → salt + hydrogen
In this equation, "salt" does not only mean table salt. In chemistry, a salt is a compound formed when the hydrogen in an acid is replaced by a metal.
在这个方程式中，"盐"不只是指食盐。在化学中，盐是酸中的氢被金属取代后形成的化合物。
The hydrogen leaves as hydrogen gas, which is why bubbles appear. The remaining part of the acid joins with the metal to form the salt.
氢以氢气形式逸出，这就是出现气泡的原因。酸的其余部分与金属结合形成盐。
3. Common Acids and Their Salts | 常见酸及其盐
At KS3 level, you need to know three common laboratory acids: hydrochloric acid, sulfuric acid and nitric acid. Each acid produces a different family of salts.
在 KS3 阶段，你需要了解三种常见实验室酸：盐酸、硫酸和硝酸。每种酸生成不同族的盐。
Hydrochloric acid makes chloride salts.
盐酸生成氯化物盐。
Sulfuric acid makes sulfate salts.
硫酸生成硫酸盐。
Nitric acid makes nitrate salts.
硝酸生成硝酸盐。
This naming rule is very useful. If you know which acid you used, you can predict the name of the salt.
这个命名规则非常有用。如果你知道使用了哪种酸，就能预测盐的名称。
4. Hydrochloric Acid: Making Chlorides | 盐酸：生成氯化物
When a metal reacts with hydrochloric acid, the salt produced is a metal chloride. For example, magnesium reacts with hydrochloric acid to form magnesium chloride and hydrogen.
当金属与盐酸反应时，生成的盐是金属氯化物。例如，镁与盐酸反应生成氯化镁和氢气。
magnesium + hydrochloric acid → magnesium chloride + hydrogen
Mg + 2HCl → MgCl₂ + H₂
Other examples include zinc forming zinc chloride and iron forming iron(II) chloride in dilute hydrochloric acid.
其他例子包括锌生成氯化锌，铁在稀盐酸中生成氯化亚铁（氯化铁(II)）。
Zn + 2HCl → ZnCl₂ + H₂
Fe + 2HCl → FeCl₂ + H₂
The Roman numeral II in iron(II) chloride tells us the iron has a charge of 2+ in this product. At KS3 you may also see it written simply as iron chloride, but iron(II) chloride is more precise.
氯化铁(II)中的罗马数字 II 表示铁在该产物中带 2+ 电荷。在 KS3 阶段你可能也看到简单写作氯化铁，但氯化铁(II) 更准确。
5. Sulfuric Acid: Making Sulfates | 硫酸：生成硫酸盐
Sulfuric acid reacts with metals to form sulfate salts. Magnesium and sulfuric acid make magnesium sulfate and hydrogen.
硫酸与金属反应生成硫酸盐。镁和硫酸反应生成硫酸镁和氢气。
Mg + H₂SO₄ → MgSO₄ + H₂
Zinc with sulfuric acid produces zinc sulfate, a compound that has uses in medicine and agriculture.
锌与硫酸反应生成硫酸锌，这种化合物在医药和农业中有用途。
Zn + H₂SO₄ → ZnSO₄ + H₂
The sulfate part of the acid carries a 2− charge, so it combines with one metal ion with a 2+ charge in these examples. This helps explain why the formula is MgSO₄, not Mg₂SO₄.
酸中的硫酸根带 2− 电荷，因此在这些例子中它与一个带 2+ 电荷的金属离子结合。这有助于解释为什么化学式是 MgSO₄，而不是 Mg₂SO₄。
6. Nitric Acid: Making Nitrates | 硝酸：生成硝酸盐
With dilute nitric acid, many metals form nitrate salts. Calcium and dilute nitric acid react to make calcium nitrate and hydrogen.
许多金属与稀硝酸反应生成硝酸盐。钙与稀硝酸反应生成硝酸钙和氢气。
calcium + nitric acid → calcium nitrate + hydrogen
Ca + 2HNO₃ → Ca(NO₃)₂ + H₂
However, nitric acid is a special case. Concentrated nitric acid can produce nitrogen oxide gases instead of hydrogen with some metals. At KS3, we usually focus on dilute acids and the general pattern, but it is good to know that nitric acid can behave differently in concentrated form.
不过，硝酸是一种特殊情况。浓硝酸与某些金属反应可能生成氮氧化物气体而不是氢气。在 KS3 阶段，我们通常关注稀酸和一般规律，但了解浓硝酸可能表现不同是很有用的。
7. Testing for Hydrogen Gas | 氢气的检验
The gas produced in metal-acid reactions is hydrogen. It is colourless and odourless, so we need a test to identify it safely.
金属与酸反应生成的气体是氢气。它无色无味，因此我们需要一个安全的检验方法来识别。
The standard test is to hold a lighted splint at the mouth of the test tube. If hydrogen is present, it burns with a distinctive "squeaky pop" sound.
标准检验方法是在试管口放一根点燃的小木条。如果存在氢气，它会燃烧并发出独特的 "爆鸣声"（squeaky pop）。
Use a small volume of gas.
使用少量气体。
Keep the test tube pointed away from people.
试管口不要对着人。
A squeaky pop is a positive result for hydrogen.
听到爆鸣声即为氢气阳性结果。
Hydrogen is flammable, so this test must be carried out carefully with teacher supervision.
氢气易燃，因此该检验必须在教师指导下小心进行。
8. The Reactivity Series and Acid Reactions | 活动性顺序与酸反应
Not all metals react with acids. Potassium, sodium, lithium and calcium react very violently, so they are not usually used in classroom experiments with acids. Magnesium, zinc and iron react steadily and are safer to observe.
并非所有金属都能与酸反应。钾、钠、锂和钙反应非常剧烈，因此通常不用于课堂酸实验。镁、锌和铁反应平稳，更适合观察。
Copper and silver do not react with dilute acids because they are less reactive than hydrogen. Gold and platinum are even less reactive and do not react with dilute acids.
铜和银不与稀酸反应，因为它们的活动性比氢弱。金和铂更不活泼，也不与稀酸反应。
A simplified reactivity series from most reactive to least reactive is:
从最活泼到最不活泼的简化活动性顺序为：
K > Na > Ca > Mg > Al > Zn > Fe > Pb > H > Cu > Ag > Au
Metals above hydrogen can react with dilute acids to release hydrogen. Metals below hydrogen cannot do this.
位于氢以上的金属能与稀酸反应放出氢气。位于氢以下的金属则不能。
9. Comparing Reaction Rates | 比较反应速率
When different metals react with the same acid, the rate of bubbling tells you about their relative reactivity. More reactive metals produce hydrogen bubbles faster.
当不同金属与同一种酸反应时，气泡产生的速率可以说明它们的相对活动性。越活泼的金属产生氢气气泡越快。
For example, magnesium fizzes rapidly in warm dilute hydrochloric acid, while zinc fizzes more slowly, and iron fizzes gently. Copper shows no bubbles at all.
例如，镁在温热的稀盐酸中快速冒泡，锌较慢，铁缓慢冒泡。铜则完全没有气泡。
Temperature also affects the rate. Warm acid makes the particles move faster and collide more often, so the reaction speeds up.
温度也会影响速率。温热的酸使粒子运动更快、碰撞更频繁，因此反应加快。
10. Safety and Practical Skills | 安全与实验技能
Acids are corrosive at high concentration and irritant when dilute. Always wear safety goggles and follow your teacher's instructions.
酸在高浓度时具有腐蚀性，稀释后也有刺激性。务必佩戴护目镜并遵守教师指示。
Key safety points include using a test tube rack, adding metal pieces one at a time, and not sealing the test tube because gas pressure could build up.
安全要点包括使用试管架、每次只加一小块金属、不要塞住试管，因为气压可能积聚。
After the reaction, the remaining liquid contains the salt dissolved in water. You can evaporate the water slowly to obtain salt crystals, but do not touch the solution with bare hands.
反应结束后，剩余液体中含有溶解在水中的盐。你可以缓慢蒸发水分得到盐晶体，但不要用手直接接触溶液。
11. Summary Table and Checkpoints | 总结表与检查要点
The table below summarises the salts formed from the three common acids.
下表总结了三种常见酸生成的盐。
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