Pretest

What is the density of a sample whose mass is 12.0 g and whose volume is 6.0ml?

m/v 12.0g/6.0ml 2.0g/ml

Pretest

Which of the following is an element? Sand Gold Water Sugar

Pretest

Differentiate heterogeneous from homogeneous mixtures.

Heterogeneous mixture- parts are noticeably different

Homogeneous mixture- parts are difficult to distinguish from each other

Pretest

Which of the following is not a step in a scientific method? Developing a procedure to test a hypothesis Drawing a a conclusion w/o any supporting

evidence Forming a testable hypothesis Making observations

Pretest

Identify tools needed to measure temperature and length.

Thermometer Ruler

Pretest

True or False: All of the following units are SI units: Meter Pound Kelvin

False!

Pretest

Density, mass, and volume are related by the equation density= mass/volume.

What equation would you use to find mass if you knew the density and volume?

Mass= density * volume

Solids, Liquids & Gases

Chapter 3.1

States of Matter

Materials can be classified as solids, liquids, or gases based on whether their shapes and volumes are definite or variable.

1. Solids

Solid is the state of matter in which a material has a definite shape and a definite volume. Changing the container doesn’t change the

shape or volume. The atoms are packed close together and are

arranged in a regular pattern.

Solid

2. Liquids

Liquid is the state of matter in which a material has a definite volume, but not a definite shape. Changing the container changes the shape, but

not the volume. The atoms are close close together, but their

arrangement is more random than in a solid.

Liquid

3. Gases

Gas is the state of matter in which a material has neither a definite shape, nor a definite volume. Changing the container changes the shape and

the volume. The atoms are spread farther apart and are not

arranged in a regular pattern.

Gases

4. Other states of matter

Plasma is the state of matter at extremely high temperatures.

Bose-Einstein Condensate (BEC) is the state of matter at extremely low temperatures.

Plasma BEC

The kinetic theory of matter says that all particles of matter are in constant motion.

Kinetic Energy is the energy an object has due to its motion. The faster an object moves, the greater its

kinetic energy is.

1. Motion in Gases

The constant motion of particles in a gas allows a gas to fill a container of any size or shape.

Particles in a gas are in constant, random motion.

The motion of one particle is unaffected by the motion of other particles unless they collide.

Forces of attraction among particles of a gas can be ignored under regular conditions.

Think of hitting balls around on a pool table.

2. Motion in Liquids

Liquids take the shape of their container because particles in a liquid can flow to new locations.

The volume of liquids is constant, because forces of attraction keep the particles close together.

Think of people walking down a hallway.

3. Motion in Solids

Solids have a definite volume and shape, because there are strong attractions between particles that restrict their motion & keep them in fixed locations. The particles vibrate, rather than bounce

around.

Think of people sitting in movie theater.

The Gas Laws

Chapter 3.2

States of Matter

Changes in the volume, the temperature, the pressure, and the number of particles have predictable effects on the behavior of a gas.

Pressure

Pressure is the result of a force spread out over an area. The SI unit of pressure is derived from the SI

units for force (Newton) and area (m2).

Pressure = N per m2

N/M2

Pascal (Pa)

Because a Pa is a small amount of pressure, scientists often use Kilopascals (kPa)

1000 Pa = 1 kPa

Collisions between particles of a gas and the walls of a container are what cause the pressure in a closed container of a gas

Think of a balloon!

Factors that Affect Gas Pressure

1. Temperature- Raising the temperature of a gas will increase

its pressure if the volume of the gas and the number of particles stay the same.

Temperature rises Kinetic energy of the particles increases The particles move faster and collide more

often with the walls of the container The faster moving particles hit the walls with

greater force =

The pressure inside the container increases

2. Volume Reducing the volume of a gas increases its

pressure if the temperature of the gas and the number of particles stays the same.

As the volume of a container decreases, particles of a gas collide more often with the walls of the container, which increases the pressure.

3. Number of Particles Increasing the number of particles will

increase the pressure of a gas if the temperature and the volume stay the same.

The more particles there are in the same volume, the greater the number of collisions and the greater the pressure.

Charles’s Law

The volume of a gas is directly proportional to its temperature in Kelvins if the pressure and the number of particles is constant.

V1/T1= V2/T2

Increase the temperature,

increase the volume

Absolute Zero??

Practice!!!

At 283 degrees Kelvin, the gas in a cylinder has a volume of 0.25 L. The gas is allowed to expand to 0.285L. What must the final temperature be for the pressure to remain constant?

What info are we given? T1= 283 K

V1= 0.25 L

V2= 0.285 L

T2= ? Pressure remains the

same, so we don’t worry about it.

What equation do we use? V1/T1= V2/T2

0.25 L/283 K = 0.285 L/T2

T2 = (0.285 L * 283 K)/.25 L

T2 = 323 K

Boyle’s Law

The volume of a gas is inversely proportional to its pressure if the temperature and the number of particles is constant.

P1V1 = P2V2

Decrease the volume,increase the pressure

Practice!!!

A gas has a volume of 5.0L at a pressure of 50 kPa. What happens to the volume when the pressure is increased to 125 kPa? The temperature does not change.

What info are we given? V1= 5.0 L

P1= 50 kPa

P2= 125 kPa

V2= ? Temperature doesn’t

change so we don’t worry about it.

What equation do we use? P1V1 = P2V2

(50 kPa)(5.0 L) = (125 kPa)V2

Divide both sides by 125 kPa

V2 = (50 kPa * 5.0 L)/125 kPa

V2 = 2.0 L

The Combined Gas Law

This law describes the relationship among the temperature, volume, and pressure of a gas when the number of particles is constant.

P1V1/T1 = P2V2/T2

Practice!!!

Gas stored in a tank at 273 K has a pressure of 388 kPa. The safe limit for the pressure is 825 kPa. At what temperature will the gas reach this pressure?

What info are we given? T1= 273 K

P1= 388 kPa

P2= 825 kPa

T2= ? Volume must stay the

same.

Start w/ this equation: P1V1/T1 = P2V2/T2

Figure out what you don’t need (volume) & re-work the equation:

P1/T1 = P2/T2

388 kPa/273 K = 825 kPa/T2

T2= (825 kPa * 273 K)/388 kPa

T2 = 580 K

Phase Changes

Chapter 3.3

States of Matter

Phase Change

A phase change is the reversible physical change that occurs when a substance changes from one state of matter to another.

6 Common Phase Changes

1. Melting

2. Freezing

3. Vaporization

4. Condensation

5. Sublimation

6. Deposition

1. Temperature & Phase Changes

The temperature of a substance does not change during a phase change. (see pg. 85)

2. Energy & Phase Changes

Energy is either absorbed or released during a phase change.

Energy is transferred between a substance & its surroundings.

The direction of the transfer depends on the type of phase change.

Endothermic Change

An endothermic change is a change in which a system absorbs energy from its surroundings.

“Endo” means “in” In an endothermic change, matter is taking

energy in. Melting, Vaporizing, Sublimation

Heat of Fusion

The heat of fusion is the energy a substance must absorb in order to change from a solid to a liquid.

Exothermic Change

An exothermic change is a change in which a system releases energy to its surroundings.

“Exo” means “out” In an exothermic change, matter is putting

energy out Freezing, Condensation, Deposition

Melting & Freezing

The arrangement of molecules in water becomes less orderly as water melts and more orderly as water freezes.

Melting = Solid Liquid How?

Freezing = Liquid Solid How?

4. Vaporization & Condensation

Vaporization = Liquid Gas

Heat of Vaporization- The energy a substance must absorb in order to change from a liquid to a gas.

There are two kinds of vaporization:

Evaporation

Evaporation = Liquid Gas Takes place at the surface of a liquid and occurs

at temperatures below the boiling point.

Vapor Pressure

Vapor pressure is the pressure caused by the collisions of particles in a vapor with the walls of a container.

Boiling

Boiling = Liquid Gas How?

Condensation

Condensation = Gas Liquid

5. Sublimation & Deposition

Sublimation = Solid Gas

Deposition = Gas Solid