Ch. 16

Matter can be divided into two categories: mixtures and substances.

Mixtures contain more than one kind of matter. Example: Cola can be separated into carbonated water, corn syrup, caffeine, etc.

Substances cannot be separated into different kinds of matter by physical means. Example: water, gold, silver, etc.

Mixtures can fit into two categories: Homogeneous: the same throughout.

Example: An unopened can of juice is the same at the top and bottom of the can.

Solutions: heterogeneous mixtures in which one thing is dissolved into something else. Examples: salt water, carbonated beverages.

Heterogeneous: different samples are not necessarily made up of exactly the same proportions of matter. Example: Chicken noodle soup. One spoonful might contain more liquid, noodles, or vegetables than another spoonful.

Suspensions: heterogeneous mixtures in which particles are floating and will eventually settle out. Examples: muddy water

Colloids: heterogeneous mixtures in which particles are floating and won’t settle out. Examples: milk, smoke.

Mixtures can be separated by physical means.

ALL mixtures (homogeneous or heterogeneous) can be separated by means of: Filtering Heating Sorting Cooling

The separation process DOES NOT change the characteristics of each component. If I separate the noodles, veggies, chicken, and broth out of my soup, they are still noodles, veggies, chicken, and broth.

Technique for separating and identifying mixtures that are or can be colored. Also called Thin layer chromatography.

It is done by:1. Placing a spot of the mixture near the bottom of a strip of

chromatography paper.2. Hanging the paper into a solution (water) so that the bottom 2

centimeters of the paper are in the solution.3. Waiting and watching. The solution will move up the paper,

separating the mixture as it goes.

Can not be separated into different kinds of matter by physical means. Elements: Substances that contain only one kind of matter are called. Example: gold, copper, iron, etc.

Compounds: Substances that are made of two or more elements that cannot be separated by physical means are called. Example: table salt – contains both sodium and chlorine. Rust (iron oxide) also cannot be separated.

Mass: the amount of matter in an object. DIFFERENT from WEIGHT: your weight is affected by gravity. Your mass is not – it will stay the same everywhere in the universe.

Measuring devices: Scales: measures the force gravity exerts on the object.

Balance: measures mass of an object by comparing it with a known mass.

Volume: measures the amount of space that an object takes up.

When measuring a LIQUID: Use things like measuring cups, graduated cylinders, or beakers.

Remember: When reading the volume, read at eye level and at the bottom of the meniscus!

To find the volume of a solid, you can: Use a mathematical formula:

Use Displacement: if it’s a weird shape, submerge it in water and measure the amount of water displaced. The volume of the object is the same as the amount of water displaced.

To find the volume, subtract the volume of the water before the object was submerged from the volume after it was submerged.

How could I measure the mass of a tennis court?

Indirect Measurement: measurement made when it is not possible to use a device to measure directly.

Remove a piece of asphalt from the court. Use the displacement method to measure the

volume of the tennis court. It’s about 1687cm3.

Use a balance to measure the mass of the asphalt.

It’s about 1.94 kg. Measure the volume of the court:

Volume of a rectangle = L x W x H. Volume = 36.51m x 18.29m x 0.075m Volume = 50.08 m3.

NOW WE SET UP A PROPORTION. MASS OF CHUNK = MASS OF COURT VOLUME OF CHUNK VOLUME OF COURT

PLUG NUMBERS INTO THE FORMULA THAT YOU KNOW. YOU MUST CHANGE 1687 cm3 TO m3 SO UNITS WILL MATCH.

1.94kg = ( X ) .001687m3 50.08m3

NOW CROSS MULTIPLY

(1.94kg)(50.08m3) = (.001687m3) (X kg)

GET X ON ONE SIDE OF THE = SIGN BY DIVIDING EACH SIDE BY .001687

(1.94kg)(50.08m3) = (.001687m3) (X kg)

.001687m3 .001687m3

MULTIPLY & DIVIDE TO SOLVE FOR kg 57,590.5kg IS THE MASS OF THE TENNIS COURT

How can I measure the mass of a piece of paper?

You can measure the mass of something small?

MEASURE OBJECT WHOSE MASS DOES NOT REGISTER ON THE BALANCE (0.0g) BY MEASURING MANY OF THE OBJECTS AND DIVIDING BY HOW MANY OBJECTS THERE ARE.

EX. 50 PIECE OF PAPER WEIGH .10 lb. DIVIDE .10 lb BY 50 TO KNOW MASS OF 1 PIECE OF PAPER

Matter is made up of different components: Molecules: the smallest part of a compound that retains the properties of that compound. Contains AT LEAST two atoms.

Atoms: the smallest parts of elements.

Atoms are ALWAYS in motion.

Since atoms make up molecules, so are they.

Movement is affected by temperature: At High Temperatures they

move fast with lots of energy. When moving faster, they bump

into each other more. At Low Temperatures they move

slow with little energy. Is there a temperature

where atoms will stop moving? Yes: Absolute Zero. It is 0°K (kelvin) or -459°F.

Matter exists in four states: Solids: the molecules vibrate, but they can’t move around and switch places. Solids retain their shape and size.

Liquids: are able to move over and around each other. Liquids have a definite volume, but no shape. They take the shape of whatever container they are in.

Gas: molecules are able to move very quickly throughout a container. Have no definite shape or size. Spread evenly throughout the space they’re in.

Plasma: The most common state of matter. Acts like a gas, but can be influenced by a magnetic field.

Rare on Earth. Occurs at extremely high temperatures.

These temperatures cause atoms to break apart. Found in stars.

Each phase changes with temperature:

Remember: atoms, and thus molecules, are always in motion. They also vibrate.

All elements exist as a solid, liquid, or gas.

When a substance changes state, ONLY the movement of the molecules change. The number of them remains the same.

The state of matter that a substance is in in influenced by its temperature. Temperature is a measure of the average energy of the molecules and their average speed.

The higher the temperature, the more energy they have and the faster they move.

As their energy and speed increases, their state changes.

Each substance has a specific temperature and pressure at which it will undergo a change of state: Melting Point: the temperature at which a substance changes from a liquid to a solid. Water = 0°C (32°F) Iron = 1538°C (2800°F)

Boiling Point: the temperature at which a substance goes from a liquid to a gas. Water = 100°C (212°F) Iron = 2861°C (5182°F)

As substance change state, certain processes are involved.

Evaporation: occurs when fast moving molecules in a liquid escape to become a gas. As high energy molecules escape as gas, heat is taken from the area immediately surrounding the substance.

The result is that anything touching the substance feels colder.

Ex. When you sweat – the sweat evaporates from your skin, cooling you down.

Condensation: when a substance changes from a gas to a liquid. Occurs as the temperature decreases. When this happens, energy is lost into the area surrounding the object, thus the area feels warmer.

Ex. Water Vapor (gas) in the atmosphere cools and forms rain drops (liquid).

Freezing: when a substance changes from a liquid to a solid.

Melting: when a substance changes from a solid to a liquid.

Sublimation: when a substance goes directly from a solid to a gas when heated. The opposite of this is called deposition.

Practice with changes of state.