Physical Science Section 3.1 Matter and Energy

1. The physical form of matter is known as its statestate. It is determined partly by how the how the substance’s substance’s particles moveparticles move.

2. Matter is made of atomsatoms and molecules molecules that are always in motion. in motion. The higher the temperature, the faster the faster the particles move. the particles move. At the same temperature, particles with more mass mass move more slowly than less massive less massive ones. ones. All these statements are part of the kinetic kinetic theory of matter. matter.

3. Particles of a solid do not move move fast enough to overcome the fast enough to overcome the strong attraction between themstrong attraction between them, so they vibrate in placevibrate in place. They can be represented by a “picture” like this:

3. Cont. Solids have a definite shapeshape and volumevolume because of the strong strong attractions between the particlesattractions between the particles.

4. Particles of a liquid move fast enough to overcome some of the some of the forces of attraction between themforces of attraction between them. The particles are able to slide past slide past one anotherone another. They can be represented by a “picture” like this:

4. Cont. Because the particles are free to move, liquids flow flow freely and take the shape of their containers. their containers.. They do not easily change volumevolume; the volume of the liquid remains remains constantconstant. NOTE: The particles of a liquid are not as

spread out as most people think. The particles are actually quite close together, but they are not organized.

5. Particles of a gas move fast enough to overcome nearly all of nearly all of the forces of attraction between the forces of attraction between themthem. The particles move independently independently of one another. They can be represented by a “picture” like this:

5. Cont. They do not have fixed shapesshapes, and their volume volume can also change. This is because the particles move fast enough to break away break away from each otherfrom each other.The gas expandsexpands to fill the space it is in. Gases can be compressedcompressed because their particles can be pressed closer together by pressure.

6. Liquids and gases are both fluidsfluids because their particles can move freely move freely past each other (they can flow.)past each other (they can flow.)

7. The sun and other stars are made of plasma. plasma. About 9999% of the universe is in this state, so it is the most abundantabundant state of matter. Particles in plasma are electricallyelectrically charged, or ionizedionized. It is defined as being free-moving ionsfree-moving ions and electronselectrons.

7. Cont. In addition to being present in the stars, plasma is found naturally in lightning, lightning, fire,fire, and aurora aurora borealis.borealis. This is a glow in the upper atmosphere atmosphere caused by the collision of high energy high energy plasma with gasgas particles.

7. Cont. When electric current is passed through gases gases plasmas are formed artificially. Gases do not conduct electric currentelectric current, but plasmas do.

Plasma TV’s contain a layer of xenon and neon that start to glow when electricity runs through them.

8. Because all particles of matter are in constant constant motion (even if they only vibrate), they have kinetickinetic energy. TemperatureTemperature is a measure of the average kinetic energy of the particles in an object. The faster the particles move, the higherhigher their kinetic energy, and the higherhigher their temperature.

8. Cont. Temperature is not determined by how much of the substance you have. how much of the substance you have.

2oC2oC

9. The total kinetic energy (thermalthermal energy) DOES depend on the number of particles present.

More coffee = more total thermal energy

10. Water can undergo multiple changes of statestate. Some of these changes requirerequire energy, and some releaserelease energy.

GASGAS

SOLIDSOLID LIQUIDLIQUID

sublimatio

n

sublimatio

n condensation

condensation

evaporation

evaporationmeltingmelting

freezingfreezing

11. Ice, liquid water, and steam all have different amounts of energyenergy, but they are all the same substance, substance, with the chemical formula HH22O.O. During a change of state, the temperaturetemperature does not change, but its energyenergy does change.

0oC

12. The melting melting point of a solid is the temperature at which it changes from a solid to a liquid. As it is heated, the particles vibrate faster vibrate faster as they gain energy, and eventually they break away from their fixed fixed positions,positions, and the solid melts. Melting point also depends on pressure.pressure.

13. Evaporation is defined as the change of state of change of state of a substance from a liquid to a gas. a substance from a liquid to a gas.

Evaporation from the surface only; lower molecules are still liquid.

13. Cont. If this happens throughout the entire liquid at a specific temperature and pressure, it is called boiling. boiling. The temperature at which this happens is called the boiling pointboiling point of that substance.

Boiling throughout the entire liquid at its boiling point

Some solids, such as dry icedry ice, change directly from a solid to a gas, in a process called sublimation.sublimation. This also happens to ice cubes in a freezer, as they change directly to a vapor.vapor.

14. The opposite can also occur, as when water vapor forms frost on the ground or on a very cold window.

115. Sublimation, meltingSublimation, melting, and boilingboiling all require energy.

16. Condensation,Condensation, the change of state from a gas to a liquid, is the opposite of evaporation. evaporation. Energy is released (given released (given off)off) as the particles slow down and come together.

17. The change of state from a liquid to a solid is called freezing.freezing. It is the opposite of melting,melting, and it releasesreleases energy as the particles slow down and line up in a pattern. Freezing and melting occur at the same same temperature.temperature.

18. During a change of state, the temperature does not changechange until the entire change is complete.

19. Mass is conserved for all physical and chemical changes. The mass of all substances after a change is the same as the mass of all substances before the change.

This is known as the law of Conservation of Mass. Mass cannot be created or destroyed.

19. Cont

20. Energy can change form but the total amount of energy present before and after the change is the same

20. Cont

• This is known as the law of conservation of energy.

20 Cont

• Energy cannot be created nor destroyed. Sometimes energy is transferred to the surroundings as heat

Section 3

21. Liquids and gases are classified as fluids. They exert pressure evenly in all directions. The unit of pressure is the pascal, and it can be calculated with this equation:

pressure = force/area

or P = F/A

22. Pressure inside a tire is caused by the force of air particles inside tire; the more air you pump into the tire, the greater the number of air particles pushing against the inside, and the greater the pressure is.

23. The SI unit of pressure is the pascal, abbreviated Pa. It is equal to a force of one Newton exerted over an area of one square meter.

24. A water bed that weighs 1050 N covers an area of 3.65 m2 on the floor. How much pressure does it exert on the floor?

Given:

Unknown:

Equation: P = F/A

Math:

Answer:

25. In a container of fluid, pressure increases with depth. Therefore, the forces pushing up on an object in the fluid are greater than the forces pushing it down. The resulting upward force is called buoyant force. All fluids exert an upward buoyant force on matter.

26. If an object is completely submerged in a fluid, the water displaced equals the buoyant force acting on an object. This concept is known as Archimedes’ Principal. If the weight of the object is greater than the buoyant force, the object will sink. If the weight of the object is less than the buoyant force, the object will float.

27. You can determine whether a substance will float or sink by comparing its density to that of the fluid. The density of a brick is about 2 g/cm3, and the density of water is 1.00 g/cm3, so the brick sinks in water. Helium is about 1/7 as dense as air, so helium floats in air.

28. A rock weighs 25 N. It displaces a volume of water that weighs 15 N. What is the buoyant force on the rock? 15N

29. Most fish have an organ called a swim bladder, which the fish can fill with gases. If the swim bladder is inflated, the fish’s volume is increased, and its density is decreased. This keeps the fish from decreased. Sharks do not have swim bladders so they must swim constantly to keep from sinking.

30. Steel is about 8 times as dense as water, so a block of steel would sink. A ship, however, floats because it has a hollow shape, which increases its volume. The mass does not change, so this decreases the ship’s density, and it floats.

31. When you apply pressure to any part of a tube of toothpaste, toothpaste usually comes out the end, because pressure is transmitted throughout the toothpaste.

Con’t

This demonstrates Pascal’s principle, which states that a change in pressure at any point in an enclosed fluid will be transmitted equally to all parts of the fluid.

32. Hydraulic devices use liquids to transmit pressure from one point to another. A small downward force is applied to a small area, and it transmits pressure to a larger area, creating a larger force.

cont

The plunger where the small force is applied travels a greater distance than the heavy load on the smaller area travels

33. Given: F1 = 160 N

A1 = 0.5 cm2

A2 = 3 cm2

Unknown: F2 = ?

Equation: F1 = F2

A1 A2

Math: 160 N/0.5 cm2 = F/3 cm2

Answer: 960 N

34. Fluids move faster through small areas than through larger areas, if the overall flow rate remains constant. This explains why water comes out of a water hose faster if you place your thumb over the end.

35. Fluids vary in the rate at which they flow. A liquid’s resistance to flow is called viscosity. A more viscous liquid has stronger attraction between its particles. Honey has a higher viscosity than lemonade. Molasses has a greater viscosity than milk.

36. As the speed of a moving fluid decreases, its pressure increases.

Section 4

List 4 unique properties of gases:

a. Expand to fill their container

b. Spread out easily and mix with one another

c. Have low densities and are compressible

d. Are mostly empty space

2. Gases exert pressure by constantly hitting each other. The battering by millions of particles adds up to a steady force. A gas under pressure will escape its container if possible, as when air rushes out of a balloon. Gases in pressurized containers can be dangerous and must be handled carefully.

3. The gas laws describe how the behavior of gases is affected by temperature, volume and pressure. These include:

A. Boyle’s law, which involves constant temperature. It states that the volume of a gas increases as the gas’s pressure decreases, and the volume decreases as the pressure increases.

• Duplicate the drawing and captions in Figure 2 in the space below

Boyle’s Law can be expressed by this statement: The product of pressure and volume is constant.

The equation for Boyles law is:

  P1V1 = P2V2

 Words:

(pressure1)(volume1)= (pressure2)(volume2)

Variables: pressure1 & volume1 refer to the initial volume and pressure

pressure2 & volume2 refer to the final

B. Gay-Lussac’s law, which involves constant volume. It states that the pressure of a gas increases as the gas’s temperature increases, and the pressure decreases as the temperature decreases.

C. Charles’s law, which involves constant pressure. It states that the volume of a gas increases as the gas’s temperature increases, and the volume decreases as the temperature decreases.

• Duplicate the drawing and captions in Figure 4 in the space below:

Boyle’s Law explains why a bubble of air is bigger at the surface of the ocean than it is deep in the ocean.

Charles’ Law explains why an inflated balloon shrinks if you put it in the freezer and pops if it gets too hot.

Gay-Lussac’s Law explains why the pressure in your tires is less in the winter and increases in the summer.

• Draw a generalized graph for each of the three gas laws: