8th grade section notes

 

 

States of Matter       

Chapter 2 Section 1

Gas

nState in which Matter changes in both shape and volume (what happens in the other 2)

nA’s & M’s move fast enough to break away from one another (Less attraction to ea. other)

nEmpty space between particles

nAmount of space can change & atoms can get forced closer together (ex: helium in a tank)

Gas Under Pressure

nPressure

nThe amount of force exerted on a given area

nThe amount of collisions of particles inside of a container

nExamples: What do you think?

Laws of Gas Behavior

nPressure must be considered when measuring gas

nBoyle’s Law

nRelationship between the volume and pressure of a gas

nRobert Boyle (17th century Irish chemist)

nAt constant temp., the volume of a gas increases as its pressure decreases

nLikewise, volume decreases as pressure increases

 

Gas Laws cont.

nCharles’s Law

nStates that for a fixed amount of gas at constant pressure, the volume of the gas increases as its temp. increases

nLikewise, the volume of the gas decreases as its temp. decreases (Balloon Lab)

 

Plasmas

nState of matter that does not have a definite shape or volume and whose particles have broken apart (What is this like?)

n99% of known matter in the universe

nIncludes sun and stars

nFacts about its properties:

nConduct electric current

nAffected by electric current

nNatural plasmas include lightning, fire, & aurora borealis

nArtificial plasmas: fluorescent lights and plasma balls

 

 

Aurora Borealis
 

 
Formulas: D= m/V     m=V*D      V=m/D
1.  D=7.13 g/cm3       m= 106.81 g     V= 
 
2.  D=11.35 g/cm3    V= 8.22 cm3      m=
 
3.  m= 153.39 g     V=8.22 cm3   D=
 
4.  m= 227.58 g     V= 25.4 cm3      D=
 
5.  m=50.29 g      V= 10cm3       D=
 
6.  m= 186.4 g     V= 20 cm3      D=
 

 
1. m=153.39 g  V=11.32 cm3  D=?   

2. m=227.58 g V=25.4 cm3  D=?

3. m=50.29 g   V=10 cm3 D= ?     

 4. m=186.4 g  V= 20 cm3  D=? 


 
Book K Introduction to Matter
    Section 2 Describing Matter


Physical Properties of matter can be observed or measured without changing the identity of the matter.

Types:
    Thermal Conductivity- ability to transfer thermal energy from one area to another.
    State- the physical form in which a substance exists, such as a solid, liquid, or gas
    Malleability- the ability to be pounded into thin sheets
    Ductility- the ability to be drawn into wire
    Solubility-the ability to dissolve in another substance
    Density—of a particular substance is always the same at a given temperature and pressure. Density of one substance is usually different from that of another substance.
        Density = mass        d = m
             Volume              V

Liquid water always has a density of 1.00 g/cm3 at 20° C and normal atmospheric pressure.
        When layering liquids of different densities, the densest layer is on the bottom and the least dense layer on top.

Physical Change is a change that affects one or more physical properties of a substance. The identity of the substance remains the same.
    Ex.
    Melting Butter or melting ice
    Dissolving kool-aid in water
    Breaking chalk into pieces

Chemical Properties describe a substance based on its ability to change into a new substance with different and new properties from the original substance.

Types:
    Flammability
    Reactivity

Chemical Change  is the actual process in which that substance changes into another substance. Irreversible by physical means.
    Evidence of a chemical change involves:
        Color changes        Sound
        Fizzing            Light    
        Foaming            Odor
        Heat

Ex.     Original Substance        Chemical Change        New Substance
    Wood                Flammability/Heat        Ash and smoke
    Raw Egg            Heat                Scrambled Egg
    Burning Gas in a Car    Heat / Reactivity        Energy to move


Book K Chapter One: Properties of Matter
Section One: What is Matter?


Matter: anything that has volume and mass. All matter takes up space.

    Volume: the amount of space taken up by matter.
Gases, liquids, and solids take up space.

Liquid volume: a Graduated Cylinder is used to measure the volume of a liquid. The curve created at the liquid’s surface inside a graduated cylinder is called a meniscus. Look at the bottom of the meniscus to read the correct volume of liquid. The units for liquid volume are liters (L) (nalgene bottle) or milliliters (mL) (pop).

Solid volume: to calculate the volume of a rectangular solid you need to measure the length, height, and width, then:
            L x W x H = Solid Volume “cubed”
Cubic means “having 3 dimensions.” The unit would be expressed as cm3 for centimeters, or m3 for meters.

•    For objects that are not rectangular, use displacement for measure volume. See “Volumania” activity.

Gas volume: Gas expands to fit the volume of the container. So find the volume of the solid container empty and full of the gas and you can calculate the gas volume:
             Container with gas Volume
         --    Empty Container Volume
        Gas  volume

    Mass: the amount of matter that something is made of. Unit is grams (g).

        Gravity: a force of attraction between objects that is due to their masses. 
            The amount of force of attraction depends on two things:
1.    mass of the object
2.    distance between them
* This is hard to detect unless you’re comparing huge objects such as the Earth and our moon. Or a huge object with a small such as a satellite and Earth.

Weight: a measure of gravitational force exerted on an object. Unit is newton (N). Use a spring scale to determine weight.
    
Mass vs. Weight: The attraction between objects decreases, as the distance between them increases.

Ex. Astronauts have both mass (they take up space) and weight (gravity is acting upon them) on Earth.
However in outer space, astronauts have the same mass (they are still taking up the same amount of space), but the weight is different because of the lack of gravity or less gravity.

So, weight depends on mass, but is not the same thing.

Inertia:
    The tendency of all objects to resist any change in motion.

    **An object at rest will remain at rest unless something causes change.
    **A moving object continues to move at the same speed and in the same direction unless something changes it’s speed or direction.

            So, mass is a measure of inertia.
    Ex.    Starting a train from rest requires a lot of power. To stop a train requires a lot of power and distance.
        Vs.
        A Mini Cooper doesn’t need as much power compared to the train because its mass is less to start it from rest. To stop a Mini Cooper required less power and less distance than the train.