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

Key Concepts

Pure Substances

A pure substance consists of a single type of particle and has a uniform composition throughout. Examples include elements like oxygen and compounds like water. Pure substances have distinct physical and chemical properties that do not change regardless of the sample size.

Mixtures

A mixture is a combination of two or more substances where each retains its individual properties. Mixtures can be classified as homogeneous, where the components are evenly distributed (like saltwater), or heterogeneous, where the components are not uniformly distributed (like salad).

Homogeneous vs. Heterogeneous Mixtures

Homogeneous mixtures have a consistent composition throughout, making it difficult to distinguish the individual components, while heterogeneous mixtures contain visibly different substances or phases. Mayonnaise, for example, is considered a heterogeneous mixture because it contains oil, egg yolk, and vinegar, which do not blend uniformly.