The term "chemicals" refers to any substance that is not a pure compound, element or mineral. This includes things like dyes, solvents, acids and bases, as well as various other substances used in laboratories for research purposes. The phrase "types of chemicals" would then refer to the different categories or classifications of these substances based on their properties, uses, and characteristics. These may include organic compounds (those containing carbon), inorganic compounds (those not containing carbon), acids, bases, salts, etc.