Chemical Equations (original) (raw)
Last Updated : 10 Apr, 2026
Chemical equations are symbolic representations of chemical reactions that express the reactants and products in terms of their chemical formulae. Symbols are also used to denote elements like the reaction's direction and the physical states of the reacting entities.
- Chemical formulas and other symbols are used to represent the initial elements, or reactants, which are written on the left side of the equation by convention, and the final compounds, or products, which are written on the right side of the equation by convention.
- From the reactant to the products is indicated by an arrow. "Yields" or "reacts to form" is just how the arrow is read.
This example shows the basic elements of any chemical equation:
- Reactants are the chemicals that undergo a reaction, and their formulas are found on the left side of the equation.
- The substances formed by the reaction are referred to as products, and their formulas are written on the right side of the equation.
- Individual reactant and product formulations are separated by plus signs (+), and the reactant and product (left and right) sides of the equation are separated by an arrow (→).
- Coefficients (numbers placed immediately to the left of each formula) represent the relative numbers of reactant and product species.
Short-Hand Method of Representing a Chemical Reaction.
- A chemical equation is a means of describing a chemical reaction using symbols and equations for the substances involved in the process.
- The example below demonstrates how to clearly understand the meaning of a chemical equation.
- Zinc sulphate and hydrogen gas are formed when zinc metal combines with dilute sulphuric acid.
Zinc + Sulphuric acid → Zinc sulphate + Hydrogen
- The symbol of zinc is Zn.
- The formula of sulphuric acid is H2SO4.
- ZnSO4 is the formula of zinc sulphate.
- H2 is the formula of hydrogen.
Zn + H2SO4 → ZnSO4 + H2
Reactants Products
- Reactants are compounds that mix or react together. Zinc and sulphuric acid are the reactants in the above reaction. In an equation, the reactants are always written on the left side with a plus sign (+) between them.
- Products are the new substances produced during a reaction. The products of the reaction are zinc sulphate and hydrogen. In an equation, the products are always written on the right side, with a plus symbol (+) between them.
- Between the reactants and the products, an arrow sign (→) pointing to the right is placed. This arrow indicates that the substances on the left-hand side of the equation are combined to produce the substances on the right-hand side. It should be obvious by now that the chemical equation is a shorthand method of representing a chemical reaction.
Balanced Chemical Equation
- In a balanced chemical equation, the reactants and products have an equal number of atoms of different elements. In other words, on both sides of a balanced chemical equation, the number of atoms of the various elements is equal.
- Zinc sulphate and hydrogen are formed when zinc combines with dilute sulfuric acid.
Zn + H2SO4 → ZnSO4 + H2
- We found that the reactants and products both contain one zinc atom.
- Two hydrogen atoms are found in reactants and two hydrogen atoms are found in products.
- Reactants and products each have one sulphur atom in them.
- Finally, the reactants have four oxygen atoms, and the product has four oxygen atoms as well.
- As a result, the reactants and products have an equal number of atoms of different elements, making the above-mentioned chemical equation balanced.
- A balanced chemical equation contains equal masses of various elements in reactants and products because the number of atoms of various elements in reactants and products is equal.
Unbalanced Chemical Equation
- The reactants and products in an unbalanced chemical equation have an uneven number of atoms of one or more elements.
- An unbalanced chemical equation, in other words, has an uneven number of atoms of one or more elements on both sides.
- Water is formed when hydrogen combines with oxygen.
H2 + O2 → H2O
| **Number of atoms of elements | **In reactants | **In products |
|---|---|---|
| **H | 2 | 2 |
| **O | 2 | 1 |
- In this equation, the reactants have two hydrogen atoms, and the products have two hydrogen atoms as well.
- However, the reactants and products have different numbers of oxygen atoms.
- The reactants, on the left side, have two oxygen atoms, but the products, on the right side, have just one.
- The preceding chemical equation is unbalanced because the number of oxygen atoms in the reactants and products is uneven.
- Due to the uneven number of atoms of various elements in reactants and products, it can be said that an imbalanced equation is one in which the masses of various elements in the reactants and products are uneven.