Short Answer

The reaction between an acid and a metal is a chemical reaction in which the acid reacts with the metal to produce salt and hydrogen gas. This is a type of single displacement reaction because the metal replaces hydrogen from the acid. It occurs commonly with reactive metals such as magnesium, zinc, and iron.

During this reaction, the metal atoms lose electrons (oxidation) and hydrogen ions from the acid gain electrons (reduction). This makes the reaction a redox reaction as well. The release of hydrogen gas is often seen as bubbles.

Detailed Explanation :

Reaction Between Acid and Metal

The reaction that occurs between an acid and a metal is a chemical process in which the metal reacts with the acid to form salt and hydrogen gas. This type of reaction is known as a single displacement reaction because the metal displaces hydrogen from the acid. It is also considered a redox reaction, since there is a transfer of electrons between the metal atoms and hydrogen ions.

This reaction is commonly observed in school laboratories and many everyday situations. It helps us understand how metals behave with acids and how important products such as salts and hydrogen gas are formed. This reaction also plays a role in corrosion, industrial production of hydrogen, and metal reactivity studies.

1. General Form of the Reaction

The general word equation for the reaction is:

Acid + Metal → Salt + Hydrogen gas

The general chemical equation is:

2H⁺ + M → M²⁺ + H₂↑

Here:

• H⁺ comes from the acid
• M is the metal
• Hydrogen gas forms as bubbles

Example

Hydrochloric acid + Magnesium → Magnesium chloride + Hydrogen
HCl + Mg → MgCl₂ + H₂

This shows how a metal replaces hydrogen in the acid.

2. How the Reaction Occurs
3. a) Metal Atoms Lose Electrons (Oxidation)

Metal atoms donate electrons and form metal ions.
Example: Mg → Mg²⁺ + 2e⁻

1. b) Hydrogen Ions Gain Electrons (Reduction)

Hydrogen ions (H⁺) from the acid accept electrons and form hydrogen gas.
2H⁺ + 2e⁻ → H₂

Because oxidation and reduction occur at the same time, this is a redox reaction.

3. Types of Acids That React with Metals

Common acids that react with metals include:

• Hydrochloric acid (HCl)
• Sulphuric acid (H₂SO₄)
• Nitric acid (HNO₃)* (dilute nitric acid reacts differently)

Note: Concentrated nitric acid does not release hydrogen gas because it is a strong oxidizing agent.

4. Metals That React with Acids

Metals high in the reactivity series react strongly with acids:

• Potassium
• Sodium
• Calcium
• Magnesium
• Aluminium
• Zinc
• Iron

Metals like copper, silver, and gold do not react with dilute acids because they are less reactive.

5. Examples of Reactions
6. a) Zinc and Hydrochloric Acid

Zn + 2HCl → ZnCl₂ + H₂

Zinc chloride and hydrogen gas are formed.

1. b) Iron and Sulphuric Acid

Fe + H₂SO₄ → FeSO₄ + H₂

Iron sulphate is produced.

1. c) Magnesium and Hydrochloric Acid

Mg + 2HCl → MgCl₂ + H₂

This reaction is fast and vigorous.

These examples show how different acids and metals form different salts.

6. Characteristics of the Reaction

• Formation of salt
• Release of hydrogen gas
• Bubbling or fizzing is observed
• Reaction rate depends on the reactivity of the metal
• Heat is often released (exothermic reaction)

The bubbles of hydrogen gas are visible signs that the reaction is happening.

7. Importance and Uses of the Reaction
8. a) Production of Hydrogen Gas

Industries use acid–metal reactions to produce hydrogen gas for fuels and chemical synthesis.

1. b) Testing Metal Reactivity

This reaction helps determine the position of a metal in the reactivity series.

1. c) Corrosion Understanding

Similar reactions occur during corrosion of metals in acidic environments.

1. d) Laboratory Demonstrations

The reaction shows displacement and redox concepts clearly.

1. e) Salt Formation

Useful salts like magnesium chloride, zinc sulphate, and iron sulphate are produced.

8. Factors Affecting the Reaction Rate

• Reactivity of the metal (more reactive → faster reaction)
• Concentration of the acid
• Temperature
• Surface area of the metal

A more reactive metal like magnesium reacts faster than a less reactive metal like iron.

Conclusion

The reaction between an acid and a metal is a single displacement reaction in which the metal reacts with the acid to produce salt and hydrogen gas. This reaction is also a redox reaction because metal atoms are oxidized while hydrogen ions are reduced. The reaction plays a major role in metal reactivity studies, hydrogen production, corrosion processes, and the formation of useful salts. Understanding this reaction helps explain many everyday chemical phenomena and laboratory experiences.