Phases of Matter

�Phases ofMatter

Matter is the �stuff� wehave been talking about for some time now.�Everything that takes up space or has mass is made of matter.� There are four states or phases of matterthat you should be familiar with.� Theyare�

�Solids -� definite shape and volume

�Liquids-take the shape of the container, so they have no definite shape.� They do have definite volume.

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�Gas-� No definite shape or volume.

�Plasma-super high energy.� Rare on earth.� Common in the Sun.

�� �Matter is always in one of these states ofmatter.� Which one depends on how muchenergy the matter has.�A gain or loss in energy cancause the matter to change phases.

Lets see how this happens.

Melting-� Phase change from asolid to a liquid.� This occurs when enoughenergy is added to a solid.� Even something as solid asrock can melt if enough heat is provided.

Freezing-Phase change from a liquid to a solid.� This occurs when energy is taken away from asolid.� When molten lava cools down, itturns into solid rock.

Evaporation-� Phase change from aliquid to gas.� This occurs when energy isadded to a liquid.� On hot summer days, puddles of water quickly turn into a gas (water vapor) anddisappears from sight.

Condensation-� Phase change from agas to a liquid.� This occurs when energy istaken away from a gas.� The water vaporfrom the puddle rises high into the air where it getscolder.� The vapor starts to condenseinto little water droplets, which eventually forms a cloud.� The water droplets on theoutside of your glass is another example of condensation.

Sublimation-Phase change from a solid directly to a gas.� When energy is added to some solids, like dry ice,the matter skips the melting phase and goes directly to a gas.� This is called sublimation.

Chemicalchange vs. Physical change

In chemistry, a physical change occurswhen a substance changes its size or shape.�An example of this would be chopping a log into tiny toothpicks.� You start out with a large piece of wood andwind up with many small pieces of wood.�You begin and end with wood.�Changing phase is also a physical change.� When you freeze water, you get ice.� Ice is just water, only in a solidstate.� You have the same thing.� It has the same properties.

In chemistry, a chemical change occurswhen a substance changes into something entirely new.� An example of this would be taking a log andburning it.� You start with wood and windup with ashes.� Ashes and wood aredifferent.�� Another example would be therusting of a nail.� You begin with ironand you get rust.� The two are not thesame. �Iron and rust have differentproperties.� One is hard and smooth, the other is flakey and rough. Getting the idea???

�A physical change is a change where

�Types of Matter

Matter can be two things,a pure substance or a mixture.

�Puresubstances:these have a fixed composition and set of physical properties.

�Mixtures: two or more puresubstances mixed together.

Puresubstances can be either elements or compounds.�Elements are also known as atoms.�Compounds are made up of more than one atom that have been chemically combined.� Water is an example.�

Pure substances:

�Elements: any matter that cannotbe broken down into further pure substances. The elements are listed on theperiodic table: we currently know of about 115. Iron and uranium are elements

�Compounds: pure substances made upof one or more elements. Water is a compound: it is made up of two hydrogenatoms and 1 oxygen atom. (H2O)

Mixturescan be either homogeneous or heterogeneous.� They arenot chemically combined!


Homogeneous: a homogeneous mixture isone that appears the same throughout. It is very well mixed.� Sea water is a homogeneous mixture of water,table salt and a variety of other compounds, stainless steel is a homogeneousmixture of iron, carbon, nickel and other elements.

Heterogeneous: mixtures that are poorlymixed.� The substances that are mixedtogether are easily seen.

Example: A banana split is a heterogeneous mixture of ice cream,bananas, whipped cream, nuts, chocolate syrup and other things. The chocolatesyrup is a homogeneous mixture ofwater, cocoa powder, sugar and other compounds.�If you look at the syrup it all looks the same.

The thing to rememberabout mixtures is that you start with some pieces, combine them, and then youcan do something to pull those pieces apart again. You wind up with the samemolecules (in the same amounts) that you started with. Compounds, on the otherhand, can not be turned back into the original parts.� There has been a chemical change.

Amixture is when two or more things are put together. There are two types ofmixtures; those containing all the "same stuff" or homogeneous, andthe other containing "different stuff" or heterogeneous. Kool-aid is a mixture where all the "parts" arethe same and is an example of the homogeneous mixture. Fruitsalad as an example of the heterogeneous mixture. So a mixture iswhen two things are put together but are not chemically combinedA solution is a homogenous mixture where onething is dissolved into another. �Asolution is made up of two parts.

Solute- the substance that getsdissolved

Solvent-the substance that does the dissolving.

Somesubstances, like sand, cannot be dissolved.�Such substances are said to be insoluble.

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Lemonadeis a solution.� It looks the samethroughout (yellow liquid).� It hasdissolved sugar (solute) in water and lemon juice (solvent).