Battery acid, also known as sulfuric acid, is a compound. It is composed of two elements, hydrogen and sulfur, that are chemically bonded together to form a new substance with different properties than the original elements. The chemical formula for sulfuric acid is H2SO4, indicating that it contains two hydrogen atoms, one sulfur atom, and four oxygen atoms. Compounds are pure substances that have a fixed composition and can be broken down into simpler substances only by chemical means.