U1 - Module 1: Searching for Differences

Question 1

What are most things in our surroundings considered?

Answer 1

complex systems

Question 2

What is an example of a complex system?

Answer 2

The air we breath

Question 3

What are most of the systems that we encounter?

Answer 3

Mixtures

Question 4

Mixtures

Answer 4

Combination of many different substances

Question 5

Homogenous Mixture

Answer 5

Uniform composition and properties

Question 6

What is an example of a homogenous mixture?

Answer 6

Drinking water

Question 7

Heterogenous Mixture

Answer 7

Composed of visibly different substances that can be in the same or different phases (solid, liquid, gas)

Question 8

What is an example of a heterogenous mixture?

Answer 8

Minerals on earth

Question 9

The properties of systems can…

Answer 9

remain constant
or
change on a regular basis

Question 10

What is an assumption used towards the chemical analysis of substances?

Answer 10

Each substance, no matter how simple or complex, has at least 1 differentiating characteristic that makes it unique.

Question 11

Differentiating Characteristic

Answer 11

Specific chemical/physical properties used to distinguish substances from each other.

Question 12

What makes a good differentiating characteristic?

Answer 12

Intensive and unique

Question 13

Intensive Properties

Answer 13

The bulk properties that do not depend on the amount of matter present.

Question 14

What are examples of intensive properties?

Answer 14

• Melting point
• Density
• Conductivity

Question 15

Extensive Properties

Answer 15

Depend on the amount of matter that is present.

Question 16

What are examples of extensive properties?

Answer 16

• Mass
• Volume
• Energy

Question 17

Boiling Point

Answer 17

The temperature at which a substance transforms from liquid to gas at a given pressure.

Question 18

What do normal boiling points consist of?

Answer 18

Boiling temperatures at atp at sea level

Question 19

Kelvin to C conversion

Answer 19

C + 273.15 = K

Question 20

atm to Pa conversion

Answer 20

Pa divided by 101325 = atm

Question 21

atm to mmHg conversion

Answer 21

mmHg divided by 760 = atm

Question 22

What is the main distinguishing characteristic focused on in this chapter?

Answer 22

Transformation of a pure substance from one phase to another at a constant pressure.

Question 23

Phase Transition/Change

Answer 23

Transformation of a substance from one state to another.

Question 24

What 2 things are true about phase change?

Answer 24

1. Chemical nature is preserved
2. Temperature can be accurately measured.

Question 25

Transition Point

Answer 25

The slope part of the heat curve - Adding energy causes temperature to increase

Question 26

Phase Transition on heat curve

Answer 26

Adding/removing energy induces a change of state, but no change in temperature.

Question 27

What is the differentiating characteristic during a phase transition?

Answer 27

The energy released per unit of mass

Question 28

The larger the change in density induced by phase transition...

Answer 28

The larger the energy transfer

Question 29

Vaporization

Answer 29

Liquid to gas

Question 30

Freezing

Answer 30

Liquid to solid

Question 31

Deposition

Answer 31

Gas to solid

Question 32

Condensation

Answer 32

Gas to liquid

Question 33

Melting

Answer 33

Solid to liquid

Question 34

Sublimation

Answer 34

Solid to gas

Question 35

cal to J conversion

Answer 35

1 cal = 4.184 J

Question 36

What is phase transition dependent on?

Answer 36

External pressure

Question 37

Phase Diagrams

Answer 37

Shows the 3 main phases and the values where they occur/co-occur.

Question 38

What does each substance have?

Answer 38

Its own phase diagram

Question 39

What do the solid lines in a phase diagram show?

Answer 39

Where phase transition occurs and specifies conditions where 2 conditions simultaneously exist

Question 40

Triple Point

Answer 40

Where the 3 lines of a phase diagram intersect, displaying where all the conditions coexist.

Question 41

What is true of the triple point?

Answer 41

The specific values of temperature and pressure at the triple point can be used as differentiating characteristics.

Question 42

When does density change?

Answer 42

As phase changes from solid to liquid

Question 43

When do liquid and gas become more alike?

Answer 43

As temperature and pressure increases

Question 44

Critical Period

Answer 44

The point at the end of the line in a phase diagram that states it impossible to observe another phase change since the liquid and gas are so alike.

Question 45

Supercritical Fluid

Answer 45

The term used for when the gas and liquid phases are indistinguishable from each other.

Question 46

Vapor Pressure Curve

Answer 46

An indirect measure of how much a liquid evaporates at a given temperature (liquid to gas phase).

Question 47

What does the vapor pressure curve trace?

Answer 47

the value of vapor pressure

Question 48

The higher the pressure of the vapor pressure curve...

Answer 48

-Higher the rate of evaporation - Larger amount of pressure exerted

Question 49

When does boiling occur?

Answer 49

When the vapor pressure of a liquid becomes equal to the external pressure - gas can escape

Question 50

What is the vapor pressure curve useful in?

Answer 50

Separating liquids

Question 51

What are the 2 methods of separation?

Answer 51

1. Filtration 2. Distillation

Question 52

Filtration

Answer 52

Based on differences in particle size Used to separate solids from liquids.

Question 53

What is true about filtration?

Answer 53

It is never complete; some solid will still pass through

Question 54

What is the efficiency of filtration dependent on?

Answer 54

The filters thickness and pore size

Question 55

Distillation

Answer 55

Based on differences in boiling points Gas is cooled down to a liquid and heated up to separate gases based on boiling points.

Question 56

Is distillation ever perfect?

Answer 56

No - have to distill the different separations collected again

Question 57

What is the normal boiling point of water?

Answer 57

100 C / 1 atm

Question 58

What is the normal freezing point of water?

Answer 58

0 C / 1 atm

Question 59

What is the normal temperature and pressure levels of the critical point?

Answer 59

0.0098 C / 4.58 mmHg

Question 60

Phase Behavior

Answer 60

The separation and identification of the components of many systems can be done using phase change points (conversion of matter) as “differentiating characteristics”.

Question 61

Physical Change

Answer 61

The observed behavior is characteristic of all substances undergoing phase change.

Question 62

When is energy released during a phase transition?

Answer 62

gas to liquid or liquid to solid - energy levels go down

Question 63

When is energy absorbed during a phase transition?

Answer 63

solid to liquid or liquid to gas - energy levels go up

Question 64

What is the usual starting point for an energy graph?

Answer 64

delta e = 0

Question 65

Phase Stability

Answer 65

A system tends to remain stable at different values of temperature and pressure.

Question 66

What happens to the boiling point at higher elevations?

Answer 66

It lowers since the pressure levels are lower.

Question 67

What effect have differentiating substances had on the development of models?

Answer 67

Oversimplified the models (sometimes wrong)