4.2 Chemical
Equation
Understand the Law of Conservation of Mass (Law of
Conservation of Matter). In a chemical reaction the total number of atoms stays
the same before and after the reaction.
Study Guide
Explain each concept
è A chemical equation describes a reaction using formulas, symbols, and coefficients.
è A balanced equation uses coefficients to illustrate the law of conservation of mass.
è
Many chemical reactions can be classified by comparing reactants with
products.
è
In synthesis reactions, the reactants form a single product.
è
In decomposition reactions, a single reactant breaks apart into
simpler products.
è
In single-replacement reactions, a more-reactive element replaces a
less reactive element.
è In double-replacement reactions, ions in two compounds switch places.