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

No, subscripts in a chemical formula cannot be fractions because they represent whole numbers of atoms in a molecule. Coefficients in a balanced chemical equation can be fractions, but it is more common to use whole numbers for easier stoichiometry calculations. Changing subscripts to balance equations is unacceptable because it changes the identity and properties of the substances involved. Instead, adjust the coefficients to balance the equation and conserve mass without altering the molecular structure.

Step-by-step solution

Question 1: Subscripts as fractions in chemical formulas

The subscripts in a chemical formula represent the ratio of atoms of each element present in the compound. They indicate the number of atoms of an element in a molecule. Since they represent whole numbers of atoms, subscripts cannot be fractions.

Question 2: Coefficients as fractions in balanced chemical equations

Coefficients in a balanced chemical equation represent the number of molecules or moles of a substance that participate in the reaction. While it is not typical to use fractions as coefficients, it is possible to have them in a balanced chemical equation. However, it is more common to use whole numbers, as they are easier to work with in stoichiometry calculations. If a balanced chemical equation has fractional coefficients, it can be multiplied by the lowest common multiple of the denominators to obtain whole number coefficients. For example, if you have a balanced equation with coefficients 1/2 and 1/3, you can multiply the entire equation by 6 to obtain whole number coefficients.

Question 3: Why is changing subscripts unacceptable for balancing equations mathematically?

Changing the subscripts of chemicals in a chemical equation in order to balance it is unacceptable because it would change the identity and properties of the substances involved. The subscripts indicate the composition of the compound and directly relate to its molecular structure. Altering them would create an entirely different compound with different chemical and physical properties. To balance chemical equations, one should always change the coefficients, not the subscripts. Adjusting the coefficients allows the number of atoms of each element to be equal on both sides of the equation without changing the identity of the substances involved. This accurately represents the conservation of mass during a chemical reaction, as dictated by the law of conservation of mass.