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A written description of the process that occurs during a chemical reaction is referred to as a chemical equation. It is written in various ways, including symbols and numerals.
Chemical equations are used to describe chemical reactions. Chemical equations feature reactants on the left, an arrow that reads “yields,” and products on the right.
The reactant components are presented on the left-hand side of a chemical equation. The production elements are supplied on the right-hand side, with a plus sign between the entities in both the reactants and the products and an arrow pointing towards the products indicating the direction of the reaction.
An example of a chemical equation is as below
2 HCl + 2 Na → 2 NaCl + H2
According to this equation, sodium and HCl combine to generate NaCl and H2. It also means that two sodium molecules are necessary for every two hydrochloric acid molecules. It also conveys that the reaction would yield two sodium chloride molecules and a single molecule of hydrogen gas for every two hydrochloric acid molecules and two sodium molecules that take part in the reaction.
How to Write a Chemical Equation
In a chemical equation, the reactants are written on the left side of an arrow, while the products of the chemical reaction are written on the right. Although certain equations may imply equilibrium with the reaction going in both directions simultaneously, the tip of the arrow normally heads toward the right or product side of the equation.
The symbols are used to represent the elements in an equation. Stoichiometric numbers are denoted by coefficients adjacent to the symbols. Subscripts denote the number of atoms of a certain element present in a chemical substance.
Participants in the Chemical Reaction:
Let’s take an example of a chemical equation. The equation given below represents the combustion of methane.
CH4 + 2 O2 → CO2 + 2 H2O
Element Symbols
To understand what is happening in a chemical reaction, you must be familiar with the symbols for the elements participating in the chemical reaction.
In the case of the above equation, C is carbon, H is hydrogen, and O is oxygen.
Left Side of the Equation: Reactants
The reactants are written on the left side of the equation. Methane and oxygen serve as the reactants in this chemical process. Their symbols are CH4 and O2.
Right Side of the Equation: Products
The products of the reaction are written on the right side. The products formed from this reaction are carbon dioxide and water. Their symbols are CO2 and H2O.
The direction of Reaction: Arrow
It is common practice to put the reactants on the left side of a chemical equation and the products on the right. The arrow between the reactants and products should point from left to right, or if the reaction is going both ways, it should point in both directions.
Balancing the Mass and Charge in an equation
Chemical equations can be unbalanced as well as balanced in nature. An unbalanced equation displays only the reactants and products, not their ratios. A balanced chemical equation has the same quantity and kind of atoms on both sides of the arrow.
Indication of the physical states
Chemicals’ physical states are frequently indicated in brackets following the chemical symbol, particularly for ionic processes. When indicating physical state, (s) represents a solid, (l) a liquid, (g) a gas, and (aq) an aqueous solution.
Provision of external energy sources
If the reaction needs energy, it is stated above the arrow. A capital Greek letter delta (Δ) is placed on the reaction arrow, indicating that energy in the form of heat is provided to the reaction. The word (hv) is employed as a sign for adding energy in the form of light. Other symbols are used to represent different forms of energy or radiation.
Balanced Chemical Equation
In a balanced chemical equation, the reactants and products contain an equal amount of atoms of various elements. In other words, the amount of atoms of each element is equal on both sides of a balanced chemical equation.
For example
Zn + H2SO4 → ZnSO4 + H2
In this equation,
As the reactants and products have an equal amount of atoms of different elements, the above-mentioned chemical equation is balanced.
As the number of atoms in reactants and products is equal, a balanced chemical equation has an equal mass of various elements in reactants and products. A chemical equation needs to be balanced to follow the law of conservation of mass.
Conclusion
A chemical equation is a symbolic description of a chemical reaction. It includes reactants and products along with chemical reagents and catalysts. A chemical equation also represents the energy released or acquired during the reaction of reactants to products.
