Chemical Reactions and equations


A number of chemical reactions taking place within and outside our body. A simple example is the process of digestion mediated by digestive  enzymes. During the process,  water and food material combine to release energy into the bloodstream. The enzymes found in the gut are responsible for many chemical processes which ultimately release energy. A chemical reaction is characterized by a change in the colour and state of the substances with or without heat energy. In some reactions, we can observe the release of gas along with the light or sound.


Chemical Equations

A chemical reaction is the result of interaction between the 2 or more reactants. In a chemical reaction, all the reactants are written on the left-hand side of the equation and the products fall under the right-hand side followed by an arrow mark. For example, reaction between magnesium and oxygen is written as Magnesium + Oxygen gas Magnesium Oxide. In this case, magnesium and oxygen are reactants and Magnesium oxide is the productA typical way of describing a chemical reaction is through the chemical equation. A chemical equation is the visual summary of processes between the reactants and the products. Writing equations using chemical formulas can help us to communicate effectively about the underlying details.  Let us elaborate on the scientific methodology of writing a chemical equation with examples.


Balancing of Chemical Equations

Balancing of chemical equations is a way by which the number of each atom of the reactants-side is equally corresponding with the number of atoms of the products in a given chemical equation. A chemical equation can be considered to be correct only if the total number of atoms of the left-hand side balance with that of the right right-hand side. 


Guidelines for balancing the chemical equations

  1. Ensure that the chemical equation is correctly written in words. For example:

    1. Magnesium + Oxygen gas Magnesium Oxide

  2. Replace the descriptive elements by substituting the chemical symbols in their respective places. Remember, the atoms must be balanced between the 2 sides at every point of the reaction. The above equation can be symbolically written as ;

    1. Mg + O2MgO (Not Balanced)   

  3. Now, inspect the LHS (reactants) and the RHS (products) to check whether both of them have an equal number of atoms of the corresponding element.

  4. In case if it is not equal, try to multiply the resultant chemical formula containing the unbalanced atoms by the LCM. For example, multiply by 2 for our case in the equation.

    1. 2Mg + O2 2MgO.

    2. During balancing of the chemical equation, always ensure that both the reactants and products retain their chemical formula.

  5. Very important, indicate the appropriate physical states of both the reactants and the products in a given chemical equation. For instance, solids are represented by (s), liquid (l), gases (g) and solutions / aqueous substances (aq).

 Hence,  2Mg(s) + O2 (g)     2MgO(s) is a balanced chemical equation.


For more details on the guidelines for writing a chemical equation, go to this page

 The stoichiometry of Chemical Reactions

In chemistry, we can write chemical reactions either by word equations or through chemical equations. A stoichiometry equation is a chemical equation in which reactants combine in proportions to form products. Stoichiometry can, therefore, be defined as the amount of reactants required or the products produced in a chemical reaction. For instance,  2NaOH (aq) + H2S (aq)→ Na2S (aq) + 2H2O (l). Where two moles of NaOH reacts with one mole of H2S to give 1 mole of Na2S and 2 moles of H2O molecules. Both one and two are referred to as the stoichiometry coefficient. In the above chemical reaction, this coefficient shows the exact number of moles that took part in the reaction. In summary, the mass of an element, its number of moles and the number of molecules are used interchangeably.



Read More


 Introduction to chemistry 


Chemical thermodynamics          


Chemical reactions


Equilibrium in chemistry


Check your understanding

  1. Name any 2 of chemical reactions takes place in our body.

  2. Write the guidelines required for balancing the chemical equations.

  3. What are the steps of balancing chemical equation?

  4. What is stoichiometry equation?





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