Chapter 4 Notes Mixtures & Solutions

(uniform composition) (variable composition) Matter Pure Substance (uniform composition) Mixture (variable composition) Elements (only one kind of atom) Compounds (atoms in consistent proportions) Homo- geneous (uniform distribution) Hetero- geneous (non-uniform distibution)

MIXTURE BASICS Mixtures are usually how you find things in nature. Rocks, the ocean, just about anything you find. They are substances held together by PHYSICAL FORCES, not chemical.

Properties of Mixtures Substances do not chemically combined Substances may change in physical appearance (but not chemical comp.) Substances can be present in any amount

Tap water is a mixture of water with other dissolved substances Tap water is a mixture of water with other dissolved substances. Distilled water is a pure substance.

MIXTURES: a physical blend of two or more pure substances Homogeneous A mixture with a completely uniform distribution. Only one phase of matter is apparent. Heterogeneous A mixture of variable, non-uniform distribution. Two visible phases of matter present.

Appear to be the same throughout Examples: Glass Air Metal Homogeneous Mixtures Appear to be the same throughout Do not separate out

Heterogeneous Mixtures Separate & settle out easily Examples: Oil & vinegar Sand in water Granite Heterogeneous Mixtures Separate & settle out easily

Colloids a homogeneous mixture Particles are mixed but not dissolved Particles are kept suspended Cloudy appearance b/c particles are hitting each & keeping them from settling out Examples = milk, toothpaste, whipped cream

Solutions type of homogeneous mixture of 2 or more substances in a single physical state Best mixed of all the mixtures Examples = salt water, air, antifreeze, powdered Tang, tea, or lemonade in water One substance that dissolves = the SOLUTE One substance that does the dissolving = the SOLVENT

Properties of Solutions Universal solvent = water Particles are small Particles cannot be separated by simple physical means Every part of a solution tastes the same Thus, particles are evenly distributed (spread out)

SOLUTIONS: homogeneous mixtures solid in solid (sand) solid in liquid (muddy water or blood) solid in gas (smoke) liquid in liquid (oil in water) liquid in gas (air freshener) gas in liquid (bubbles) gas in gas (air)

Solubility Soluble = a substance that dissolves Insoluble = a substance that does not dissolve The ability of the solvent to dissolve the solute at a specific temperature = solubility Increase temperature  increase solubility

Compare the following:

Pure elements Elements made of single atoms An element made of molecules Mixture of two elements Mixture of three elements Pure compounds Mixture of two compounds