Mixtures Physical combinations of two or more different substances. –variable compositions –Examples: soft drinks, soil, brass, and air Mixtures have two compositions: –Homogeneous (solutions) –Heterogeneous (colloids and suspensions) Each component retains its own identity and properties. Mixtures can be separated through physical means.

Separation of Mixtures There are many different methods used to separate mixtures. Filtration –separation based on difference in particle size. –solid part is trapped by filter paper and the liquid part runs through the paper

Distillation –Separation based on differences in boiling point. –Example: alcohol/water mixture

Types of Mixtures Mixtures can be classified as either heterogeneous (visibly distinguishable parts) or homogeneous (visible indistinguishable parts). Heterogeneous mixtures = granite, fruit cocktail, Italian salad dressing –Colloids scatter light (Tyndall Effect) –Suspensions will settle out or separate over time Homogenous mixtures = Powerade, brass (alloy), air, French salad dressing Homogenous mixtures are also called solutions.