Unit Three

Question 1

How do hot and cold packs work?

Answer 1

Hot packs- chemical reaction that releases energy (exo)

Cold packs- chemical reaction that takes in energy (endo)

Question 2

What is the x and y axis on a heating and cooling curve

Answer 2

Temp is y

Time/ heat added is x

Question 3

What is the opposite of sublimation

Answer 3

Deposition

Question 4

What is the opposite of vaporization

Answer 4

Condensation

Question 5

What is the opposite of fusion

Answer 5

Solidification

Question 6

What are the x and y on phase diagrams

Answer 6

X axis is temp

Y axis is pressure

Question 7

What is the critical point

Answer 7

Temp at which it is impossible to liquefy the substance no matter pressure

Question 8

What is triple point

Answer 8

Where all three phases are at equilibrium, same temp and pressure

Question 9

At constant temp what would you do to cause a substance to change from liquid to solid

Answer 9

Increase pressure

Question 10

If it’s not a phase change, it’s a

Answer 10

Temperature change

Question 11

Thermochemistry

Answer 11

The study of energy changes associated with chemical reactions

Question 12

Heat

Answer 12

The transfers of thermal energy between two bodies at different temps

Question 13

Thermal energy

Answer 13

Energy associated with random movement of atoms of molecules

Question 14

System

Answer 14

The specific part of the universe that one is studying

Question 15

Surroundings

Answer 15

The rest of the universe, everything but the system

Question 16

Universe

Answer 16

The combination of the item under investigation and the immediate factors that can influence it

Question 17

Universe=

Answer 17

System plus surroundings

Question 18

Types of systems

Answer 18

Open, closed, isolated

Question 19

Open system

Answer 19

Allows transfer of both energy and mass

Question 20

Closed system

Answer 20

Energy can leave but mass can not

Question 21

Isolated system

Answer 21

Mass not energy transfer can happen ( no such thing)

Question 22

Enthalpy (H)

Answer 22

Is the total energy of a system, some of which is stored as chemical energy in the chemical bonds

Question 23

T or F energy absorbed from broken bonds never equal that released in making new bonds

Answer 23

T

Question 24

Exothermic

Answer 24

Release more energy put in

Question 25

Endothermic

Answer 25

More energy put in than our

Question 26

Triangle H is

Answer 26

Heat given off or absorbed during reaction, H products- H reactants

Question 27

Released has + or - energy

Answer 27

Negative

Question 28

Calorimetry

Answer 28

The temp of a liquid inside a well insulated container (calorimeter) is measured before and after a reaction

Question 29

Specific heat capacity

Answer 29

The amount of energy required to raise the two of one gram of a substance by one degree

Question 30

Water specific heat

Answer 30

4.18j/g•c

Question 31

Density of water is

Answer 31

One gram equals one milliliter

Question 32

Sublimation

Answer 32

Unusual phase change, specific process occurs when a solid goes directly into a gas without going through the liquid phase
Ex dry ice, carbon dioxide

Question 33

Deposition

Answer 33

Solid formed directly from vapor, same heat added same as sublimation except negative

Question 34

Why does it take more heat to boil water rather than melt ice

Answer 34

The attraction is stronger between a solid and liquid. Takes more energy because molecules are more spread out in boiling

Question 35

What is the formula for phase changes

Answer 35

Q= mol* triangle H

Question 36

What is the formula for solid/liquid/gas

Answer 36

Q=mc triangleT

Question 37

Triangle H units

Answer 37

Kj/mol