Bell Ringer Place “Learning the Equipment” Lab on the left side of your desk. I will come around and stamp it. Define and give an example of the following words: Matter Mass Weight Volume

Mixtures, Compounds and Pure Substances

Vocabulary Matter – anything composed of atoms Examples: people, cars, food Mass – measure of how much matter in an object (use a balance) Examples: number of grams Weight – measure of gravity’s pull on matter (use a scale) Examples: 150 pounds, 4 Newtons Volume – measure of how much space is taken up Examples: 15 mL, 500 cubic centimeters

Classification of Matter Matter Mixtures Pure Substances Homogeneous Heterogeneous Elements Compounds Mixtures Mixtures

Which is it? Compound Mixture Element

Pure Substance A substance with constant composition. Can be classified an either an element or as a compound. Element Elements are composed of only one kind of atom. It cannot be separated into two or more substances by ordinary chemical (or physical) means. The term ordinary chemical means excludes nuclear reactions. Examples: Iron (Fe), copper (Cu), and oxygen (O2).

Compound A substance that contains two or more elements, in definite proportion by weight. The term molecule is often used for the smallest unit of a compound that still retains all of the properties of the compound.

Classification of Matter Matter Mixtures Pure Substances Homogeneous Heterogeneous Elements Compounds Mixtures Mixtures Compound – made from atoms that are chemically bonded together. Can be separated by chemical change, but not physical means. Represented by a formula and a chemical name. Examples: H2O, CO2, NaCl

Mixture Two or more substances, combined in varying proportions - each retaining its own specific properties. The components of a mixture can be separated by physical means. i.e. without the making and breaking of chemical bonds. Examples: Air, table salt thoroughly dissolved in water, milk, wood, blood, and concrete.

All Mixtures are separated through physical or mechanical means All Mixtures are separated through physical or mechanical means. This is NOT a chemical process!!! The pure substances are separated, but no new substances are made.

heterogeneous mixtures - components not uniformly mixed homogeneous mixtures components uniformly mixed also called solutions

Separation of Mixtures: All mixtures can be separated through PHYSICAL means. Some mixtures even separate themselves!

Separation of Mixtures: Filtration: the process of using a filter to mechanically separate a heterogeneous mixture.

Separation of Mixtures: Centrifugation: A centrifuge separates a colloid by spinning it. After a successful centrifugation, the solid precipitate settles to the bottom of the test tube and the solution is clear.

Separation of Mixtures: Distillation: separates solutions based on differing boiling points Desalinization: separates salt from a solution

Chromatography

Separating mixtures Filtration- separate solids from liquids with a barrier Decanting is filtering without filter paper. Distillation- separate because of different boiling points Heat mixture Catch vapor in cooled area Chromatography- different substances are attracted to paper or gel, so move at different speeds