Classify each of the following as a pure substance or a mixture. If a mixture, indicate whether it is homogeneous or heterogeneous: (d) iodine tincture.

Key Concepts

Pure Substances

A pure substance consists of a single type of particle and has a uniform and definite composition. Examples include elements like gold and compounds like water. Pure substances have consistent properties such as melting and boiling points, which do not change regardless of the sample size.

Mixtures

A mixture contains two or more different substances that are physically combined but not chemically bonded. Mixtures can be classified as homogeneous, where the composition is uniform throughout (like saltwater), or heterogeneous, where the composition varies (like a salad). The components of a mixture retain their individual properties.

Iodine Tincture

Iodine tincture is a solution of iodine in alcohol, commonly used as an antiseptic. It is classified as a homogeneous mixture because the iodine is evenly distributed throughout the alcohol, resulting in a consistent appearance and composition. Understanding this classification helps in identifying the nature of the solution and its applications.