“Matter And Energy” page 77

The state, or physical form, of a substance is determined partly by how the substance’s particles move.

According to the kinetic theory of matter, all matter is made of atoms and molecules. These atoms and molecules act like tiny particles that are always in motion.

The following rules determine their speed:

› The higher the temperature of the substance is, the faster the particles move.

› At the same temperature, more massive particles move slower than less massive ones.

The kinetic theory helps you to understand the differences between the three states of matter: solid, liquid, and gas.

Particles in a solid vibrate in place

Particles in a liquid are closely packed, but they can slide past each other.

Gas particles are in constant motion and do not usually stick together.

You can classify matter as a solid, a liquid, or a gas by determining whether the shape and volume are definite or variable.

Solids have a definite shape and volume.

Liquids change shape, not volume.

Gases change both shape and volume.› Liquids and gases are fluids (the particles in them can

move past each other)

Plasma is the most common state of matter.› About 99% of the known matter in the universe (sun

and stars included) is made of plasma.

› Plasma is a state of matter that does not have a definite shape or volume.

› Particles in plasma are electrically charged, or ionized. Found in lightning, fire, and the aurora borealis A lot like gases, except plasma can conduct electric

currents.

Energy is the ability to change or move matter, or to do work.

The energy of motion is called kinetic energy.

According to the kinetic theory, all matter is made of particles—atoms and molecules—that are constantly in motion.

Because they are in motion, all particles of matter have kinetic energy.

Temperature is a measure of the average kinetic energy of the particles in an object.

Particles of matter are constantly moving, but not at the same speed.

When measuring temperature, you are measuring the average kinetic energy.› The more kinetic energy, the higher the temperature.

The total kinetic energy of the particles that make up a substance is thermal energy.

The total kinetic energy (thermal energy) of a substance depends on the number of particles in that substance.

3.1 Concept Review Page 81 #’s 2, 4, 6

Changes of State page 84

The identity of a substance does not change during a change of state, but the energy of a substance does change.

A transfer of energy known as heat causes the temperature of a substance to change.› If enough energy is added/removed, a substance will

change state.

The melting point is the temperature at which a substance changes from solid to liquid. › Depends on Pressure

› The temperature at which a liquid boils is the liquid’s boiling point.

Evaporation is the change of a substance from a liquid to a gas.

Solids can also change directly into gases in a process called sublimation.› Example: Dry Ice (Solid carbon dioxide gaseous

carbon dioxide)

Melting, evaporation and sublimation all require ENERGY!

•Condensation is the change of state from a gas to a liquid.

•For a gas to change into a liquid, the particles clump up, energy is released from the gas and the particles slow down.

•The condensation point of a gas is the temperature at which the gas becomes a liquid.

--Example: Condensation on your drinking glass.

During freezing, energy is also released.› Liquid Solid

The temperature at which a liquid changes into a solid is the substance’s freezing point.

Temperature is constant during a change of state.

Solid Liquid : Melting Solid Gas : Sublimation Liquid Gas : Evaporation Liquid Solid : Freezing Gas Liquid : Condensation

Energy can change forms during physical and chemical changes, but the total amount of energy present before and after a change is the SAME!

Mass and energy are both conserved. Neither mass nor energy can be created or destroyed.› Fundamental laws of Physical Science.

Law of Conservation of Mass› Mass cannot be created or destroyed.› The total mass of the reactants must equal

the total mass of the products.

Law of Conservation of Energy› Energy cannot be created or destroyed.

**Mass and Energy are CONVERTED to other forms. They are not created or destroyed!

3.2 Concept Review 3.2 Review page 88 #’s 4, 5

Fluids page 89

Pressure is the amount of force exerted on a given area of surface.

Fluids exert pressure evenly in all directions.

The SI unit of pressure is the pascal.› one pascal ( 1 Pa) is the force of one newton exerted over

an area of one square meter ( 1 N/m2)

Work on this with your group! Calculate the pressure of an enclosed gas on

which a force of 250 N is exerted over an area of 5 m2. Give the answer in Pascals.

All fluids exert an upward buoyant force on matter.

Results from the fact that pressure increases with depth.

The net upward force is the buoyant force.

*The buoyant force on an object in a fluid is an upward force equal to the weight of the fluid that the object displaces.

If the object suspended in the water is more dense than the water, then the object will sink.

*A change in pressure at any point in an enclosed fluid will be transmitted equally to all parts of the fluid.› IF the pressure in a container is increased at any

point, the pressure increases at all points by the same amount.

› P1 = P2

› F1 / A1 = F2 / A 2

Hydraulic devices use liquids to transmit pressure from one point to another.

› Can multiply forces

› Transmit pressure more efficiently than gases

Work on this in your GROUP! In a car’s liquid-filled hydraulic brake system, the

master cylinder has an area of 0.5 cm2, and the wheel cylinders each have an area of 3.0 cm2. If a force of 150 N is applied to the master cylinder by the brake pedal, what force does each wheel cylinder exert on its brake pad?

Fluids move faster through small areas than through larger areas, if the overall flow rate remains constant.

Fluids also vary in the rate at which they flow.

Viscosity is a liquid’s resistance to flow.

The stronger the attraction between a liquid's particles is, the more viscous the liquid is.

EX: Honey flows slower than lemonade because honey has a higher viscosity than lemonade.

Bernoulli’s principle: As the speed of a moving fluid increases, the pressure of the moving fluid decreases.

› Described in the 18th century by Daniel Bernoulli (Swiss mathematician)

3.3 Concept Review 3.3 Review page 94 #s 8, 9

Behavior of Gases page 96

Gases expand to fill their containers. They spread out easily and mix with one another. They have low densities and are compressible. Unlike solids and liquids, gases are mostly empty space.

Gases exert pressure on their containers.

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

The gas laws will help you understand and predict the behavior of gases in specific situations.

The relationship between the volume and pressure of a gas in known as Boyle’s law.

*For a fixed amount of gas at a constant temperature, the volume of a gas increases as the gas’s pressure decreases. Likewise, the volume of a gas decreases as the gas’s pressure increases.› Volume and pressure are INVERSELY proportional.

Pressure multiplied by volume is constant (if temperature is constant).

Boyle’s Law: (Pressure1)(Volume1) = (Pressure2)(Volume2 )

P1 and V1 represent the initial volume and pressure, while P2 and V2 represent the final volume and pressure.

Work with your group! A flask contains 155 cm3 of hydrogen at a

pressure of 22.5 kPa. Under what pressure would the gas have a volume of 90.0 cm3 at the same temperature? (recall that 1 cm3 = 1ml).

*The pressure of a gas increases as the temperature increases, if the volume of the gas does not change. The pressure decreases as the temperature decreases.› They are DIRECTLY proportional to each other.

**For a fixed amount of gas at a constant pressure, the volume of the gas increases as the gas’s temperature increases. Likewise, the volume of the gas decreases as the gas’s temperature decreases.

3.4 Concept Review 3.4 Review page 101 #’s 4,7,10