Why is it not possible to balance an equation by changing the subscript on a substance, say from H₂O to H₂O₂?

Verified step by step guidance

1. Understand the role of subscripts in a chemical formula: Subscripts indicate the number of atoms of each element in a molecule. Changing a subscript alters the identity of the compound, creating a completely different substance with different chemical properties.
2. Recognize the purpose of balancing a chemical equation: The goal is to ensure the law of conservation of mass is obeyed, meaning the number of atoms of each element is the same on both sides of the equation. This is achieved by adjusting coefficients, not subscripts.
3. Consider the implications of changing a subscript: For example, changing H₂O (water) to H₂O₂ (hydrogen peroxide) would mean you are no longer working with the same compound. This fundamentally changes the reaction and violates the principle of balancing the original equation.
4. Focus on adjusting coefficients: Coefficients are numbers placed in front of chemical formulas to indicate the quantity of molecules or moles. Adjusting coefficients allows you to balance the equation without altering the identity of the substances involved.
5. Apply this understanding to any chemical equation: Always preserve the subscripts as they define the chemical identity of the substances. Use coefficients to balance the equation while maintaining the integrity of the compounds.

Key Concepts

Chemical Formula

A chemical formula represents the composition of a substance, indicating the types and numbers of atoms present. For example, H₂O indicates two hydrogen atoms and one oxygen atom, while H₂O₂ indicates two hydrogen atoms and two oxygen atoms. Changing the subscripts alters the identity of the substance, leading to different chemical properties and reactions.

Law of Conservation of Mass

The Law of Conservation of Mass states that mass is neither created nor destroyed in a chemical reaction. This principle requires that the number of atoms of each element must be the same on both sides of a chemical equation. Changing subscripts would violate this law, as it would change the number of atoms and thus the mass of the reactants and products.

Balancing Chemical Equations

Balancing chemical equations involves adjusting coefficients (the numbers in front of compounds) to ensure that the same number of each type of atom appears on both sides of the equation. This process maintains the integrity of the substances involved while adhering to the Law of Conservation of Mass. Changing subscripts instead of coefficients would misrepresent the actual substances and their quantities.