Aadya Isai

Introduction

Salts are important chemical compounds used in daily life, industries, medicines, and fertilizers. One method of preparing salts is by reacting a metal with an acid. In this reaction, the metal replaces the hydrogen present in the acid to form a salt and hydrogen gas.

Equation:

Metal + Base —> Salt + Hydrogen gas

Process of Preparing Salts Using Metal and Acid:

Step 1 — Acid is taken

First, a dilute acid is taken in a beaker.

Example:

• Hydrochloric acid (HCl)

The acid contains:

• hydrogen

• another part called chloride

Step 2 — Metal is added

A metal such as zinc is added to the acid.

Example:

• Zinc granules are added into hydrochloric acid.

Step 3 — Metal replaces hydrogen

This is the main process.

The zinc is more reactive than hydrogen, so zinc pushes hydrogen out of the acid and takes its place.

Before reaction:

• Hydrogen is joined with chloride.

After reaction:

• Zinc joins with chloride.

• Hydrogen leaves as gas.

So:

• zinc + chloride = zinc chloride (salt)

• hydrogen escapes as bubbles

Step 4 — Hydrogen gas is released

The released hydrogen gas forms bubbles in the solution.

This bubbling is called effervescence.

Step 5 — Salt solution forms

After the reaction, the beaker contains zinc chloride dissolved in water.

This is called a salt solution.

Step 6 — Heating the solution

The solution is heated gently to remove water by evaporation.

Step 7 — Salt crystals are obtained

When the solution cools, solid salt crystals are formed.

Example reaction

Zn + 2HCl —> ZnCl₂ + H₂

• Zn = zinc metal

• HCl = hydrochloric acid

• ZnCl₂ = zinc chloride salt

• H₂ = hydrogen gas