Mixtures

Admit Slip What is the difference between a homogeneous and heterogeneous mixture?

Today’s Objectives: Students will be able to: Define, compare and contrast mixtures, heterogeneous mixtures, homogeneous mixtures, phases Describe how to separate mixtures

Agenda Homework Check/Review Notes Mixture Questions Exit Slip

Notes A mixture is a physical blend of two or more components. Therefore it is not a pure substance. The ratio of components in a mixture can vary. Mixtures can either be heterogeneous or homogeneous mixtures.

Notes A heterogeneous mixture does not have a uniform composition (makeup) throughout the sample. Ex: Chicken noodle soup A homogeneous mixture does have a uniform composition throughout and is also called a solution. Ex. Air, milk, vinegar

Notes A phase is any part of a sample with uniform composition and properties. Heterogeneous mixtures have more than one phase but homogeneous mixtures have only one phase.

Notes Mixtures can be separated by using the physical properties that the components do not have in common. (Examples on the next slides)

Filtration Filtration is used to separate mixtures when components have different sizes.

Distillation Distillation is a fancy word for boiling. Distillation is used when the components of the mixture have different boiling points and can be separated when they boil at different times.

Freezing Freezing can be used to separate mixtures because different components often have a different freezing temperature (melting point).

Evaporation Evaporation is similar to distillation/boiling but without the fancy equipment. The water from a saltwater solution will evaporate and just leave salt in a beaker.

Dissolving Dissolving works to separate mixtures when one component may dissolve in water or another solvent and another component would not dissolve.

Magnetism Mixtures can be separated by magnetism when some components are attracted to a magnet and others are not.

Chromatography Mixtures can be separated by chromatography when the components, due to their sizes, will travel at different speeds through another medium (paper or a gel).

Question 1 Which of the following is an example of a container that is filled with a pure substance rather than with a mixture? A. a tire filled with air  B. a jar filled with salt water  C. a balloon filled with helium  D. a glass filled with chocolate milk

Question 2 Which of the following is a heterogeneous mixture? Milk salt water A salad Air

Question 3 Which of the following is a homogenous mixture? Chicken salad Syrup A pile of leaves Water and sand

Exit Slip/HW Writing to Persuade Write a paragraph in support of this statement: Dry tea is a mixture, not a pure substance. Include at least two pieces of evidence to support your argument.