Question

Can the subscripts in a chemical formula be fractions? Explain. Can the coefficients in a balanced chemical equation be fractions? Explain. Changing the subscripts of chemicals can balance the equations mathematically. Why is this unacceptable?

Short answer

Subscripts in a chemical formula cannot be fractions, as they represent the number of atoms of each element in a molecule, and atoms are indivisible. Coefficients in a balanced chemical equation can be fractions, but it is more common to use whole numbers for simplicity. Changing subscripts to balance equations is unacceptable because it alters the identity of the compound and would not accurately represent the chemical reaction taking place. Instead, we adjust the coefficients to satisfy the law of conservation of mass while maintaining the identity of the compounds involved.

Step-by-step solution

Understanding Chemical Formula Subscripts

A chemical formula represents the proportions of atoms for each element in a compound. The subscripts indicate the number of atoms of each element present in one molecule of the compound. As atoms are indivisible entities, we cannot have a fraction of an atom in a molecule. Therefore, subscripts in a chemical formula cannot be fractions. They must always be whole numbers.

Understanding Coefficients in a Balanced Chemical Equation

Coefficients in a balanced chemical equation represent the stoichiometric ratios of the reactants and products involved in the chemical reaction. While it is more common to use whole numbers as coefficients for simplicity, it is not incorrect to use fractional coefficients. When coefficients are fractions, it is often simpler to multiply all coefficients by the same factor, usually the lowest common denominator, to obtain whole number coefficients.

Why Changing Subscripts for Balancing Equations is Unacceptable

Changing the subscripts in a chemical formula would alter the identity of the compound. Balancing a chemical equation is meant to reflect the law of conservation of mass, which states that the total mass of reactants in a chemical reaction must equal the total mass of products. By altering the subscripts, we would be changing the nature and proportions of the elements in each compound, which would not accurately represent the chemical reaction taking place. Instead, we adjust the coefficients to maintain the identity of the compounds involved and still satisfy the law of conservation of mass.