What are chemical reactions

Chemical reactions are the processes by which chemicals interact with one another to form new chemicals with different compositions, as defined by the definition above. A chemical reaction, in its most basic definition, is the process by which reactants are transformed into products. When it comes to chemical reactions, the chemical properties of an element or compound- the ways in which a compound or element undergoes changes in composition- are what determine how they behave.

A chemical reaction is typically represented by a chemical equation, which depicts the transformation of reactants into products in a chemical reaction. The reactants are represented on the left hand side of the equation, and the products are represented on the right hand side of the equation. A typical chemical reaction is represented mathematically by stoichiometric coefficients, which indicate the relative amounts of products and reactants involved in the reaction in percentages. A parenthetical note of the compound’s state of 2 is followed by each compound: (l) for liquid, (s) for solid, and (g) for gas, followed by the compound itself. The symbol (aq) is also frequently used to represent an aqueous solution, which is a solution in which compounds have been dissolved in water. The following are examples of possible reactions:

A(aq)+B(g)→C(s)+D(l)

In the preceding example, the reactants A and B reacted to form the products C and D, which are referred to as the products.

Two conditions must be met in order to write an accurate chemical equation:

It is necessary to write each product and reactant using its chemical formula, for example, H2

The number of atoms of each element on both sides of the equation must be the same on both sides of the equation. Coefficients are used in front of chemical formulas to help balance the number of atoms in the formula, for example, 2Mg+O2→2MgO.

Types of reactions

1) Decomposition reactions

Molecular or compound decomposition occurs when molecules or compounds are broken down into two or more simpler chemically new substances, known as decomposition products. Consider the electrolysis of water as an example. When water is electrolyzed, it decomposes into hydrogen and oxygen, which have completely different properties from that of water.Reaction – 

2H2O (electricity) → 2H2 + O2

2)Combination Reaction 

A combination reaction is a chemical reaction in which two or more molecules are combined to form a new substance by combining their chemical properties (compound). The reactions of combination and decomposition are diametrically opposed to one another. In the case of magnesium ribbon (or magnesium), when it is burned, it produces grey-black ash containing magnesium oxide. 

Reaction – Mg + O2→ 2MgO

3) Combustion reactions

Exothermic reactions such as combustion release energy in the form of heat, which is why they are called combustion reactions. It is a chemical reaction that occurs between fuel and an oxidant (usually atmospheric oxygen) and results in the production of smoke, water, and heat in general. We can see this in action when we burn methane, which produces carbon dioxide and water as byproducts.

Reaction – CH4 + 2O2 → CO2 + 2H2O

4) Neutralisation reactions

When acid and base react with each other, salt and water are formed as a result of this reaction. For example, when hydrochloric acid reacts with sodium hydroxide (base), it produces sodium chloride (salt) and water as a result of their reaction.

Reaction- HCl + NaOH →NaCl +H2O

5)Single displacement reactions

During single displacement reactions, more reactive metal is displaced from its salt by less reactive metal, which results in the formation of salt. The products of these reactions can be determined through the use of reactivity series. An elemental series in which the elements are arranged in decreasing order of their reactivity is known as a reactivity series. It means that the elements present at the top of this reactivity series are more reactive than the elements present at the bottom of the reactivity sequence. A single displacement reaction, such as the reaction of potassium with magnesium chloride, is an example of chemical reaction. As a result of potassium’s greater reactivity than magnesium, it displaces magnesium from its salt in the reaction described above. Potassium is found at the very top of the reactivity series, and it is the element with the highest reactivity. 

Reaction –  2K + MgCl2 → 2KCl + Mg

6)Double displacement reactions

During a double displacement reaction, two aqueous ionic compounds exchange their ions (mostly cations), resulting in the formation of two new compounds. For example, when potassium nitrate reacts with aluminium chloride, it produces aluminium nitrate and potassium chloride as byproducts.

Reaction – KNO3+ AlCl3 ↔️    Al(NO3)3 + KCl

7) Precipitation reactions

During these reactions, a solid precipitate is formed that cannot be removed with water. Precipitation reactions occur when two soluble salts in aqueous solutions combine to form an insoluble precipitate, which is then washed away. It is calculated that the reaction 

AgNO3(aq) + KCl(aq) → AgCl + KNO3 (aq)

8)Redox Reaction 

 Redox reactions are chemical reactions in which both oxidation and reduction take place at the same time, and they are classified as such. The addition of oxygen is referred to as oxidation, while the addition of hydrogen is referred to as reduction (or removal of oxygen). In a separate article with the title ‘Oxidation and Reduction,’ we have already discussed the concepts of oxidation and reduction. A redox reaction is exemplified by the reaction of copper oxide with hydrogen in this case. In this reaction, hydrogen has undergone oxidation, gaining oxygen atoms, whereas copper oxide has undergone reduction, losing oxygen atoms.

Conclusion

Chemical reactions are the processes by which chemicals interact with one another to form new chemicals with different compositions.A chemical reaction is typically represented by a chemical equation, which depicts the transformation of reactants into products in a chemical reaction.Molecular or compound decomposition occurs when molecules or compounds are broken down into two or more simpler chemically new substances, known as decomposition products.Exothermic reactions such as combustion release energy in the form of heat, which is why they are called combustion reactions.During single displacement reactions, more reactive metal is displaced from its salt by less reactive metal, which results in the formation of salt. The products of these reactions can be determined through the use of reactivity series.Redox reactions are chemical reactions in which both oxidation and reduction take place at the same time, and they are classified as such.