II. Classification of MatterMatter is classified on the basis of its characteristics and properties.

Many forms of matter but all classified into one of two major categories:

Pure Substance or Mixture

We tell the difference by if they can be separated physically

A. Pure Substance – matter with a fixed composition and definite (same) properties

Every sample has same composition(every sample has same ratio of atoms)

Every sample has same characteristics

Cannot be broken down by physical actions such as boiling or melting; only by decomposition reactions

Ex: Hydrogen, Helium, Carbon, Gold Ex of compounds: carbon monoxide, carbon dioxide, pure water and table salt (sodium chloride).

Can be an element or a compound

If the substance CAN be separated by chemically into simpler compounds or elements, it is a compound. Ex: H2O, NaCl (table salt)

If it can NOT be separated chemically, then it is an element. Ex: Helium, Carbon

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Ex: Is grape juice a mixture or pure substance?

In chemistry grape juice is not a pure substance. It is a mixture of many pure substances like water, sugars, and acids. It can be physically separated.

B. Mixture – a combination of more than one kind of matter physically combined (NOT chemically)

Each kind of matter retains its identity and properties; mixture is combination of the properties of the components

Parts can be in any proportion, but must be specified

Ex: 4% sodium solution 7% sodium solution

A chemical reaction does NOT occur

Ex: sand and sugar sugar and water

Mixtures can be broken down by physical actions.

Common physical actions are: evaporation* (common for separating water out of a mixture)filtrationcentrifugationmagnetismchromatographydistillationdecantationextractionrecrystallization

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Separation by filtration. A mixture of a solid and a liquid is poured through a porous

medium, in this case filter paper. The liquid passes through the paper while the solid

remains on the paper.

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A simple apparatus for the separation of a sodium chloride solution (salt water) into its components. Boiling the solution evaporates the water, which is

condensed, then collected in the receiving flask. After all the water has boiled away, pure sodium chloride

remains in the boiling flask.

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Separation of ink into components by paper chromatography. (a) Water begins to move up the paper. (b) Water moves past the ink spot, dissolving different components of the ink at

different rates. (c) Water has separated the ink into its several different components.

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1. Homogeneous Mixtures Same composition and

properties throughout Known as solutions when one

part dissolves into another part

ex: salt with water brass – mix of copper

and zinc

Solutions can NOT be separated by filtration

Solution Parts:Solvent – does the dissolving

Solute – substance dissolved (lesser quantity)

Solutions exist as any combination of solids, liquids or gasses

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2. Heterogeneous Mixtures

do not have uniform or consistent composition; uneven distribution

all parts are NOT the same

ex: sand and water

Chicken noodle soup – every spoonful is different

Raisen Bran Cereal ©– every spoonful is different

Types of Heterogeneous Mixtures

a) suspension – particles are so large they will settle out (due to gravity) unless constantly stirred.

Particles can be filtered out

Ex: Mud in water

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Muddy water after settling

Muddy water

b) colloids– particles are intermediate in size (between solutions and suspension)

do not dissolvedo not settle outlook homogeneous to the naked

eye but are heterogeneousnon uniform arrangementcolloidal particles pass through

filterstoo small for light microscope but

larger than atomsEx: mayonnaise, milk or jello

(do not need to shake)

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(a) Milkconsists of visible particlesin a non uniform arrangement.(b) Salt water isan example of a homogeneousmixture. Ions andwater molecules are in aSodium uniform arrangement.

3. Miscible vs. ImmisciblePertains to liquid mixtures

miscible – 2 or more liquids that

are able to dissolve into each other in various proportions

immiscible – liquids that do not mix into each other

MATTER

Can it be physically separated?

Homogeneous Mixture(solution)

Heterogeneous Mixture Compound Element

MIXTURE – physically combined

PURE SUBSTANCE

yes no

Can it be chemically decomposed?

noyesIs the composition

uniform?

noyes

Colloids Suspensions

Courtesy Christy Johannesson www.nisd.net/communicationsarts/pages/chem

ImmiscibleMiscible