Chapter 7, Problem 6STP

Summary Introduction

To determine : The correct coefficient for HCl in the given chemical reaction.

Introduction : The reaction between methane and chlorine gas results in the formation of HCl and CCl₄. When scientists write chemical reactions, they express each component of the reaction in a chemical equation. A chemical equation shows the reactants on the left side of the arrow and the products on the right side of the arrow.

Answer to Problem 6STP

C. 4

Explanation of Solution

In a chemical reaction, matter cannot be created or destroyed. This is law of conservation of mass. Therefore, the equations must be balanced to show balance of mass. The number of atoms of each element on the reactant side must be equal to the number of atoms of the same element on the product side. Coefficients are used to balance the number of atoms. In the case of given reaction, we can see that there are 4 hydrogen atoms in methane. To balance the number of hydrogen atoms, we must put a coefficient of 4 before HCl.

  

Conclusion

A. 1- If we put 1 as a coefficient before HCl, the number of hydrogen atoms in reactant is 4 and in product it will be only 1. So this will be an unbalanced. Hence, this is not a correct option.

B. 2- If we put 2 as a coefficient before HCl, the number of hydrogen atoms in reactant is 4 and in product it will be only 2. So this will be an unbalanced equation. Hence, this is an incorrect option.

D. 8- If we put 8 as a coefficient before HCl, the number of hydrogen atoms in reactant is 4 and in product it will be 8. So this will be an unbalanced equation. Hence, this is an incorrect option.