Unit 2 Test Review
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Created by:
colleengast on September 22, 2011
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43 terms
Terms | Definitions |
|---|---|
 Element | A pure substance that cannot be separated in simpler substances by physical or chemical means. |
| Compound | A pure substance that is a combination of two or more elements that are combined chemically |
| Homogeneous Mixture (solution) | Has constant composition in a single phase. Ex: Salt water, lemonade |
| Heterogeneous Mixture | Individual substances remain distinct. (Not a single phase) Ex: Milk (fat) Brick and woods |
| Freezing | Liquid to solid (warming) |
| Melting (fusion) | Solid to liquid (cooling) |
| Vaporization | liquid to gas (cooling) |
| condensation | gas to liquid (warming) |
| sublimination | solid to gas (cooling) |
| deposition | gas to solid (warming) |
| Triple Point | All three phases of solid, liquid and gas are in equilibrium |
| Critical point | The point in a phase diagram that indicates the temperature above which a substance never exists in its liquid state, regardless of pressure. |
| iron and oxygen combine to for rust | chemical property |
| iron is more dense than aluminum | physical property |
| magnesium burns brightly when ignited | chemical property |
| oil and water do not mix | physical property |
| mercury melts at -39 degrees celsius | physical property |
| crushing an aluminum can | physical change |
| recycling used aluminum cans to make new cans | physical change |
| aluminum combining with oxygen to make aluminum oxide | chemical change |
| water freezing and forming ice | physical change |
| burning wood | chemical change |
| water boiling and forming steam | physical change |
| Filtration | Using a poruos barrier to separate a solid from a liquid |
| Decanting | a technique used to help separate the liquid from the solid |
| Distilation | separation of homogeneous mixture of liquids by using the differences of boiling points of substances involved |
| crystallization | formation of pure solid particles from a solution containing the dissolved particles. |
| chromatography (paper & ink lab) | separates mixtures using a solvent (water) that carries a solute (ink) up a strip of paper |
| Explain how water (a compound) can be separated into the elements oxygen gas & hydrogen gas. | Hoffman apparatus produces a chemical change called electrolysis. Electric current splits H2O |
| Explain why water evaporating from your skin will make your skin feel cooler. | Energy is taken from the skin to evaporate the water, making the skin cooler |
| Explain how sublimination is used to freeze-dry foods. | Fresh food is frozen and placed in a container with a vaccuum pump. The pressure reduces, ice sublimes & is removed. |
| Substance | Matter with a uniform and unchanging composition |
| physical property | characteristic that can be observed or measured without changing the composition |
| chemical property | The ability of a substance to combine with or change into one or more substances. |
| solid | definite volume & shape |
| liquid | Flows and has constant volume and takes shape of the container. |
| gas | to definite volume or shape |
| physical change | takes place after a substance, without changing it's composition |
| chemical change | one or more substances changing into new substances |
| describe situations that demonstrate evidence of a chemical change | Rusting, burning, odor |
| Physical changes of copper | Reddish brown, shiny |
| chemical changes of copper | forms green copper carbonate when it contacts moist air. Forms a deep blue solution |
| Distance of dye divided by the distance of solvent = | RF |
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