Module 1

Question 1

Central Goal

Answer 1

Recognize distinctive properties of chemical substances that can be used to identify and separate them

Question 2

homogeneous mixtures

Answer 2

have uniform composition and properties
ie. clean air and drinking water

Question 3

heterogeneous mixtures

Answer 3

composed of visibly different substances that can be in the same or different phases
ie. minerals on earth

Question 4

intensive properties

Answer 4

properties that do not depend on the amount of substance; not all of them can be differentiating characteristics but most are
ie. melting point, density, conductivity, temperature, pressure

Question 5

extensive properties

Answer 5

properties that depend on the amount of substance; these are NOT differentiating characteristics
ie. mass, volume

Question 6

good differentiating characteristics

Answer 6

• unique values for each substance
• do not vary with size of the sample
• can be selectively measured

Question 7

boiling point

Answer 7

the temperature at which a substance transforms from liquid to gas at a given pressure; at which a substance transforms into a liquid as it cools down from a gas

Question 8

normal boiling points

Answer 8

boiling temperatures at atmospheric sea level

Question 9

Celsius to Kelvin

Answer 9

K = C + 273.15

Question 10

phase transition / phase change

Answer 10

chemical nature of a substance is preserved; substance goes from one phase to another

Question 11

Does a substance’s temperature change during a phase transition?

Answer 11

No; at a phase transition, the energy added or removed to a substance will induce a change of state WITHOUT altering the actual temperature of the system.

Question 12

melting

Answer 12

solid to liquid

Question 13

boiling

Answer 13

liquid to gas

Question 14

sublimation

Answer 14

solid to gas

Question 15

solidification

Answer 15

liquid to solid

Question 16

condensation

Answer 16

gas to liquid

Question 17

deposition

Answer 17

gas to solid

Question 18

physical change

Answer 18

the chemical nature of the substance does not change with a transformation

Question 19

How does pressure affect phase transitions?

Answer 19

The values of the external pressure around a substance can change the temperatures at which a substance transitions.

Question 20

phase diagrams

Answer 20

Graphical representations of a substance’s stability & phase change during certain temperatures & pressures.

Question 21

triple point

Answer 21

The point at which three different phases of a substance can coexist with each other under certain conditions.

Question 22

critical point

Answer 22

The point at which the characteristics of a substance during gas & liquid phases become identical.
The critical point occurs at a certain temperature & pressure for each substance.

Question 23

supercritical fluid

Answer 23

When the gas and liquid phase of a substance is indistinguishable. This occurs when temperatures and pressures are higher than the critical point.

Question 24

vapor pressure

Answer 24

The pressure that a vapor of a substance exerts when it evaporates from a liquid in a sealed container.
When the vapor pressure of a liquid is equal to the external pressure on the liquid, then boiling occurs. This is b/c the gas can freely escape.

Question 25

vapor pressure curve

Answer 25

The liquid-to-gas transition line in a pressure-temperature phase diagram

Question 26

filtration

Answer 26

The mechanical separation of solid substances and fluid substances (liquid or gas).
Efficiency largely depends on filter’s thickness and pore size

Question 27

crystallization

Answer 27

Formation of a solid phase is induced by changing the temperature or concentration of components in a mixture, OR by adding other substances.

Question 28

distillation

Answer 28

Involves a phase change from liquid to gas and reconversion of the separated substances to the liquid phase.

Question 29

atm to mmHg

Answer 29

1 atm = 760 mmHg