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Reactants and Products

  • Last Updated : 26 Oct, 2021

A chemical reaction takes place when the bonds between reactant molecules are broken and new bonds are established between product molecules, resulting in the creation of the new substance.

Chemical Reactions: When two or more molecules combine to generate a new product, it is called a chemical reaction.

Reactants are molecules that combine to form new compounds, whereas products are the new compounds that form. Chemical reactions are important in a variety of industries, customs, and even our daily lives. A chemical change must occur in a chemical reaction, as is common with physical changes like precipitation, heat production, colour change, and so on.

A reaction can occur between two atoms, ions, or molecules in which they form a new bond without destroying or creating an atom, but a new product is formed from reactants. Pressure, temperature, and reactant concentration all have an effect on the rate of the reaction.

Chemical Equations: As there are so many chemical reactions all around us, a nomenclature was created to make expressing a chemical reaction in the form of a chemical equation easier. A chemical equation is a mathematical statement that represents the production of a product from reactants while also indicating the conditions under which the reaction was carried out. 

The reactants are on the left, and the products are on the right, with one-headed or two-headed arrows connecting them. Consider a reaction.

A + B → C + D


  • A and B are the reactants, and 
  • C and D are the products of their reaction. 

Reactants are identified in a chemical equation by their chemical formula. A chemical equation must be balanced to ensure the law of conservation of mass, which means the number of atoms on both sides must be equal. This is the method by which the equation is balanced.

A chemical reaction’s two main components are reactants and products. Reactants are substances that initiate a chemical reaction. The chemical species that can be detected after the reaction has been completed are referred to as products. Chemical reactions are classified into three types: acid-base reactions, redox reactions, and combustion reactions. 

As a result, depending on the kind of reaction, the same reactant may produce multiple products at times. The primary difference between reactants and products is that reactants are consumed during the reaction, whereas products are produced as a result of the reaction.

What are Reactants?

Reactants are chemical species that serve as the catalyst in a chemical reaction. During the course of a chemical reaction, reactants are consumed. 

None of the reactants may be present in the reaction mixture at the conclusion of the reaction, although some of the reactants may be present at the end.

Colourless or coloured reactants can exist. Depending on the nature and circumstances of the reaction, they can produce either colourless or coloured compounds. A chemical reaction’s reactants might exist in solid, liquid, or gaseous phases. Reactants differ depending on the sort of response.

Types of Reactions and Reactants

  • Combustion Reactions: Combustion reactions produce reactants that are extremely flammable chemical species.
  • Decomposition Reactions: Reactants in decomposition reactions are larger molecules than the products of the reaction.
  • Acid-Base Reactions: Acids and bases are the reactants in these reactions.
  • Redox Reactions: Oxidizing and reducing agents are the reactants. Buffer solutions are sometimes employed to keep the pH of the reaction mixture stable.
  • Synthesis Reactions: Synthesis processes use smaller molecules as reactants than they do as products.
  • Precipitation Reactions: The reactants of precipitation reactions are usually liquids.
  • Exothermic Reactions: The potential energy of the reactants in these chemical processes is greater than that of the products.
  • Endothermic Reactions: The potential energy of the reactants in these reactions is lower than that of the products.

What are Products?

Products are substances that are created as a result of a chemical reaction. These byproducts may be ions or molecules. The result of a chemical reaction might exist in the solid, liquid, or gaseous phases.

Colourless or multicoloured products are available. The colour of the result is determined by the type of reactants used in the reaction. The number of products present in a reaction mixture always rises as the reaction progresses.

Types of Reactions and Products

  • Combustion Reactions: For complete combustion (of hydrocarbons), the products of combustion reactions are frequently carbon dioxide and water, and carbon monoxide for partial combustion.
  • Decomposition Reactions: The products of decomposition processes are smaller molecules than the reactants.
  • Acid-Base Reactions: These reactions invariably produce salt and water as byproducts.
  • Redox Reactions: The products are oxidised versions of reactants and reduced forms of reactants. Water is frequently used as a product.
  • Precipitation Reactions: Precipitation reactions produce solid precipitates or suspensions.
  • Synthesis Reactions: Synthesis reactions produce larger molecules than reactants.
  • Exothermic Reactions: The potential energy of the products of these chemical reactions is lower than that of the reactants.
  • Endothermic Reactions: These reactions’ products have higher potential energy than the reactants.

Examples of Reactants and Products

In a reaction, reactants are what you start with. They differ from what you get after the reaction takes place. Any chemical reaction involves both reactants and products.

  1. The wax of a candle and the oxygen in the air are reactants in a combustion reaction. Carbon dioxide and water vapour are the byproducts.
  2. When methane gas is burned, the reactants are methane (CH4) and oxygen in the air (O2). The reaction produces carbon dioxide (CO2) and water (H2O).
  3. The reactants in the formation of water are hydrogen (H2) and oxygen (O2) gas. Water is the product (H2O).
  4. Carbon dioxide (CO2) and water are the reactants in photosynthesis (H2O). Glucose is the product (C6H12O6). It should be noted that sunlight is not a reactant. Reactants are matter (atoms, molecules, and ions) rather than energy.

Identifying Reactants and Products in Chemical Equations

To identify the reactants and products in a chemical equation, look at the reaction arrow. The arrow points from left to right in a reaction that only proceeds forward. The reactants are on the left side of the arrow, while the products are on the right. A chemical species that appear on both sides of a reaction (such as solvent or spectator ions) is neither a reactant nor a product. In the following reaction, A and B are reactants, and C is the product:

A + B → C

There does not, however, have to be more than one reactant. A is the reactant in this reaction, while B and C are the products:

A → B + C

In a balanced chemical equation, the number and type of atoms are the same for the products and the reactants. For example, the number of hydrogen and oxygen atoms in the reactants (H2 and O2) and the product is the same (H2O).

Difference Between Reactant and Product

Chemical reactants are the starting element for a chemical reaction.Products are the byproducts of chemical reactions.
Reactants are consumed throughout the process.The reaction’s products are not absorbed.
During the response, the quantity of reactants in the reaction mixture decreases quickly or slowly.The quantity of products present in the reaction mixture increases rapidly or gradually.
At the start of the reaction, only reactants are present.At the start of the reaction, no products emerge in the reaction mix.
At the end of the reaction, reactants may or may not be present in the solution combination.At the end of the reaction, the products are discovered in the solution blend.

Sample Questions

Question 1: What is meant by a chemical reaction?


A chemical reaction occurs when two or more molecules collide with the proper orientation and enough force to form a new product. This process involves the breaking and forming of atom bonds. Compounds that interact to form new compounds are referred to as reactants, while the newly formed compounds are referred to as products.

Question 2: What is electrolytic decomposition?


Electrolytic decomposition is the process of decomposing any molecule using electricity. This is useful when we need to separate molecules that dissociate at high temperatures. Sodium chloride is one such example. Sodium chloride dissociates at high temperatures but easily breaks apart during electrolytic decomposition.

Question 3: Differentiate between single displacement and double displacement reactions?


A single displacement reaction occurs when one or more elements in a compound replace another element. A double displacement reaction, on the other hand, involves two ion exchanges between compounds, resulting in the formation of two new compounds.

Question 4: How do we balance a chemical equation?


  • Make a note of the unbalanced chemical reaction. If the unbalanced chemical reaction is not given, write down the skeletal equation using the components of the chemical reaction that are mentioned.
  • Take note of how many atoms are on each side of each element’s reaction. The number of atoms is represented by an element’s subscript. If the number of atoms on the reactant side is not equal to the number of atoms on the product side, the equation is not balanced. Because this violates the law of conservation of mass, we must balance the chemical reaction.
  • In the chemical reaction, add coefficients to the compounds or elements so that the number of atoms on both sides of the reaction matches for all constituent elements. Keep in mind that oxygen and hydrogen atoms should be balanced last because they are present in a variety of compounds and trying to fix that ratio first will complicate things even more.

Question 5: What is the difference between reactant and reagent?


Reactant and reagent are terms that are frequently used interchangeably. Technically, the two words do not have the same meaning. In analytical chemistry, a reagent is a substance that is added to cause a chemical reaction or to test whether one has occurred. Reagents are not always consumed in a reaction. Although solvents, catalysts, and substrates may be present in a reaction, they are not considered reactants or products.

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