Chapter 9, Problem 117A

Explain how an equation can be balanced even if the number of reactant particles differs from the number of product particles.

Interpretation Introduction

Interpretation:

The balancing of equation needs to be explained if number of reactant and product particles are not same in numbers.

Concept introduction:

In a chemical reaction, the reactants are written on the left side of the equation and the product is written on the right side. The product and the reactants contain an arrow between them showing the proceeding of the reaction from the reactants to the products.

A chemical equation is balanced by balancing the number of moles of each element on the reactants and on the products according to the law of conservation of matter.

Answer to Problem 117A

An equation can be balanced, by adjusting the number of coefficients in both the sides of the reaction.

Explanation of Solution

According to law of conservation of matter, the quantity of each of the elements present in the reaction do not change in a chemical reaction.

To balance an equation, one has to calculate the number of moles of each element in the reactions and then place coefficients in such a way that the both the reactants and the products has the same number of elements.

For example, in the reaction,

$\text{K}\left(s\right)+{\text{Cl}}_{\text{2}}\left(\text{g}\right)\to \text{2KCl}\left(\text{aq}\right)$ the left-hand side has only one K and the right-hand side to 2, i.e. the quantity of K is not balanced. So, it can be balanced by giving coefficient 2 to $\text{K}\left(\text{s}\right)$ to balance the reaction. Amount of $\text{Cl}$ is already balanced in the reaction.

Therefore, the balanced chemical equation is as follows:

$\text{2K}\left(s\right)+{\text{Cl}}_{\text{2}}\left(\text{g}\right)\to \text{2KCl}\left(\text{aq}\right)$

Conclusion

An equation can be balanced, by adjusting the number of coefficients in both the sides of the reaction.