Chemical Reactions: Their Significance and Representation

A chemical reaction is an action between two chemical substances in which the bonds of each substance are broken inside the reactant molecules, and new bonds are created inside the product molecules. This reaction forms a new substance. Chemical reactions are everywhere in our surroundings and inside us. They are in the form of the metabolism of the food we intake to how the food we get from plants, all are results of chemical reactions. Chemical reactions happen within; however, its effects can be visible outside too.

For example, a burning candle changes both physically and chemically. Please light a candle and observe it turn to wax slowly with time. If you cover the candle with a vessel, the fire will extinguish. In the example, the burning of the candle is a chemical reaction, and changing the candle to wax is a physical change. When a physical change happens, there is a change in the state of the substance. When a chemical change occurs, there is a high probability of a new substance being formed, in which either energy is given out or absorbed. Thus, we can say that chemical changes also bring about certain physical changes.

Basic Concepts of Chemical Reactions

Below are some of the most fundamental concepts that students need to know regarding chemical reactions:

• A chemical reaction is a process in which two or more molecules of two substances react and may create a new product.
• Chemical compounds that react with each other to produce new compounds are known as reactants, and the newly formed compounds are called products.
• Chemical reactions play a vital role in various industries, cooking and other daily activities. Chemical compounds in nature are continuously happening like rusting iron, fermentation of grapes into wine etc.
• When a chemical reaction takes place, there must be a chemical change generally seen with physical changes like heat production, precipitation, state change, colour change etc.
• There can also be that a reaction occurs between two atoms forming a new bond while no atom is destroyed or a new one created, but still, a new product is created from the reactants.
• The rate at which a reaction happens depends on internal and external factors like temperature, pressure, the concentration of reactants, etc.

What are Chemical Equations?

Due to the large number of chemical reactions taking place around us, a name was derived to express a chemical reaction and was called a chemical equation. A chemical equation is a mathematical placement highlighting the new product formation from the compounds reacting while following certain conditions for how the reaction has been conducted.
Consider the example of a magnesium ribbon. If you burn a magnesium ribbon in oxygen, it is converted into magnesium oxide. This explanation of a chemical reaction in a sentence is quite long and may confuse you. Thus, it is written in a shorter and more direct form. The easiest method to do so is to convert it into the form of an equation. The equation for the above example is – Magnesium + Oxygen → Magnesium oxide. The chemical substances that change in the reaction, magnesium and oxygen, are the reactants. The new substance is magnesium oxide, formed as a new product during the reaction.
An equation describes the conversion of reactants into products with the help of an arrow placed between them. The reactants are written on the left-hand side with a positive sign (+) between them. The products are written on the right-hand side, also with a positive sign (+) between them. The arrowhead points towards the products and shows the direction of the reaction.
You must have observed that magnesium ribbon burns with a dazzling white flame and changes into a white powder. This powder is magnesium oxide. It is formed due to the reaction between magnesium and oxygen in the air.

Types of Chemical Reactions 

We have learnt that when a chemical reaction, atoms of one element do not change into those of another element. Nor do atoms disappear from the mixture or appear from elsewhere. Chemical reactions involve the breaking and making bonds between atoms to produce new substances.

Combination Reaction

A combination reaction is a reaction in which combustible material is reacted with an oxidizer to create a new oxidized product. An oxidizer is a chemical that fuel requires to burn, and it is generally oxygen

Decomposition Reaction

A decomposition reaction is the type of reaction in which a single component further breaks down into multiple new products. Specific changes in the environment’s energy have to be created like light, heat, or electricity by breaking bonds of the compound.

Displacement Reaction

A displacement reaction occurs between an acid and a base, creating salt and water as the new products. The molecule of water thus formed is by the combination of OH– ions and H+ ions. When a strong acid and a base undergo a neutralization reaction, the overall pH of the products is 7.

Redox Reaction

A Reduction Oxidation (Redox) reaction is a type of reaction in which electrons transfer between the chemical components. For example, electrochemical cell-like redox reaction between Zinc and Hydrogen. A zinc atom reacts with 2 ions of (+) charged hydrogen to which electrons get transferred from zinc atom and hydrogen becomes a stable molecule and Zinc ion is the product.

Precipitation or Double-Displacement Reaction

Precipitation reaction is the type of double-displacement reaction in which two chemical compounds react and their anions and cations interchange places, forming two new products. 

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