Final answer:
The transformation of a substance into a new substance is evidence of a chemical reaction, involving new chemical bonds and potentially irreversible change.
Step-by-step explanation:
Yes, the conversion of a substance into a new substance always indicates that a chemical reaction has occurred. This is because a chemical change involves the breaking of chemical bonds in the starting materials, known as the reactants, and the formation of new chemical bonds to create new materials, called the products. For a chemical reaction to be confirmed, we can observe changes such as the evolution of gas, color changes, temperature changes, the formation of a precipitate, or a change in the properties of the substances involved.
A chemical equation represents this transformation from reactants to products, and must be balanced according to the law of conservation of mass. Unlike physical changes, which might also involve energy transfer but do not result in the creation of new substances, chemical reactions often produce noticeable changes that cannot be easily reversed, such as burning or rusting.