Phases of Matter

· Phases of Matter

Matter is the “stuff” we have 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 matter that you should be familiar with. They are…

· Solids à definite shape and volume. Matter is tightly packed and only vibrate.

· Liquidsà take the shape of the container, so they have no definite shape. They do have definite volume. Matter moves around, but still close together.

· Gasà No definite shape or volume. Matter moves quickly and is spaced far apart.

· Plasmaàsuper high energy. Rare on earth. Common in the Sun.

Matter is always in one of these states of matter. Which one depends on how much energy the matter has. A gain or loss in energy can cause the matter to change phases.

Lets see how this happens.

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

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

Evaporation- Phase change from a liquid to gas. This occurs when energy is added to a liquid. On hot summer days, puddles of water quickly turn into a gas (water vapor) and disappears from sight.

Condensation- Phase change from a gas to a liquid. This occurs when energy is taken away from a gas. The water vapor from the puddle rises high into the air where it gets colder. The vapor starts to condense into little water droplets, which eventually forms a cloud. The water droplets on the outside 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.

· Types of Matter

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

· Pure substances: these have a made of one type of atom or compound.

· Mixtures: two or more pure substances mixed together. No new properties.

Pure substances 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.

Things that are chemically combined have gone through a chemical change. A chemical change occurs when two things are combined and something entirely new forms. This is different from a physical change, which is when the size or shape of something changes. If you chop a log into toothpicks, you still have wood. This is a physical change. If you burn the wood instead, you get ash. It is not wood anymore. You can’t re-burn ash or make a boat out of it. So it has become something totally new. It is chemically different and has chemically changed.

Mixtures can be either homogeneous or heterogeneous. They are not chemically combined! The things that are mixed together still have all of their original properties.

Mixtures:

· Homogeneous: a homogeneous mixture is one that appears the same throughout. Sea water is a homogeneous mixture of water, table salt and a variety of other compounds, stainless steel is a homogeneous mixture of iron, carbon, nickel and other elements. It looks like one thing. You cannot see all of the parts.

· Heterogeneous: Does not appear the same throughout. You can see the different things making it up. A salad is an example. You can see the lettuce, the tomatoes, the cheese, the olives. It is easy to see the parts.

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

The thing to remember about mixtures is that you start with some pieces, combine them, and then you can do something to pull those pieces apart again. You wind up with the same molecules (in the same amounts) that you started with.

A mixture is when two or more things are put together. There are two types of mixtures; those containing all the "same stuff" or homogeneous, and the other containing "different stuff" or heterogeneous. Kool-aid is a mixture where all the "parts" are the same and is an example of the homogeneous mixture. Fruit salad as an example of the heterogeneous mixture. So a mixture is when two things are put together but are not chemically combined

A solution is a mixture in which a physical change has taken place but the components can be recovered. Meaning that if you mix salt and water the salt is not the same nor is the water the same but you can reclaim the salt and the water. Saltwater is mixture that is homogeneous, meaning that it is the same all the way through it. A solution is a homogeneous mixture.

SOLUTIONS ARE HOMOGENEOUS MIXTURES. They are made from a solute and solvent.

Solvent-substance that does the dissolving…like water

Solute-the thing that gets dissolved. Like sand.

Some things don’t dissolve in water. They are insoluble. Other things do dissolve. They are soluble.