Characteristics of Chemical Reactions

Unit: Chemical Reactions and Equations

What is a Chemical Reaction?

The transformation of a chemical substance into another chemical substance is known as a chemical reaction. A chemical reaction in which bonds are broken in the reactant and forming new bonds in the product to get new substances. For example, the rusting of iron, the setting of milk into curd, the digestion of food, respiration, etc.

What are the Reactants and Products?

The substances which take part in a chemical reaction are called reactants. The new substances produced as a result of a chemical reaction are called products.

For example: A + B → C + D

Here, A and B are the reactants, which react to form the products C and D.

Let’s take a chemical reaction: the burning of sodium in the air to form sodium monoxide.

4Na(s) + O₂(g) → 2Na₂O(s)

Here, Na and O₂ are the reactants, and Na₂O is the product.

What is the Chemical Equation?

A chemical equation is the symbolic representation of a chemical reaction in the form of symbols and formulae.

Chemical Reactions are classified into several categories:

There are several different sorts of reactions:-

Combustion reaction
Decomposition reaction
Neutralisation reaction
Redox Reaction
Precipitation or Double-Displacement Reaction
Synthesis reaction

The characteristics of chemical reaction:

In all chemical reactions, the transformation from reactants to products is accompanied by various characteristics, which are

Evolution of gas.
Formation of a precipitate.
Change in colour.
Change in temperature.
Change in state.
Formation of new substances.

Evolution of gas: Some chemical reactions are characterized by the evolution of a gas.

When zinc metal is treated with dilute hydrochloric acid, hydrogen gas is evolved. The hydrogen gas burns with a pop sound.

Zn (s) + 2HCl (dilute) → ZnCl₂ (aq) + H₂(g)

Formation of precipitate: Some chemical reactions are characterized by the formation of precipitate, which is insoluble.

When silver nitrate solution is mixed with a solution of sodium chloride, silver chloride precipitate is formed.

AgNO₃ (aq) + NaCI (aq) → NaNO₃ (aq) + AgCI (s)

In this simulation, we will be studying the characteristics of chemical reactions involving precipitation reaction, evolution of gas, and change in colour and temperature. Let’s study this in more detail in this experiment.

FAQs on Characteristics of Chemical Reactions

Q1: What is the displacement reaction?

Answer: Displacement reaction is a chemical reaction in which a more reactive element displaces a less reactive element from its compound.
For example: Zn + 2HCl → ZnCl2 + H2

Q2: What is the characteristic of the following chemical reaction?

Pb(NO3)2 (aq) + 2KI (aq) → PbI2 (s)(↓) + 2KNO3 (aq)
Answer: When potassium iodide reacts with lead nitrate solution to form a yellow precipitate lead iodide.The formation of precipitate indicates that a chemical reaction has taken place.”