unit 9 thermochemistry

Question 1

calorimeter

Answer 1

device used to measure heat absorbed or released

Question 2

calorie

Answer 2

quantity of heat needed to raise the temperature of 1g of water by 1 degrees Celsius

Question 3

Joule

Answer 3

SI unit of energy

Question 4

enthalpy

Answer 4

heat content of a system at constant pressure

Question 5

specific heat

Answer 5

quantity of heat needed to raise the temperature of 1g of a substance by 1 degrees Celsius

Question 6

heat capacity

Answer 6

quantity of heat needed to raise the temperature of an object by 1 degrees Celsius

Question 7

molar heat of fusion

Answer 7

amount of heat needed to melt one mole of a solid at constant temperature

Question 8

sublimation

Answer 8

process by which a solid changes directly to a gas

Question 9

exothermic reaction

Answer 9

releases heat energy

Question 10

example of exothermic reactions:

Answer 10

combustion, rain, freezing

Question 11

what side is the heat energy (delta H) on in an exothermic reaction?

Answer 11

the right side/product side

Question 12

what is enthalpy?

Answer 12

The heat energy change (delta H) that takes place when reactants go to products.

Question 13

what does a positive enthalpy mean?

Answer 13

heat is absorbed during the reaction, endothermic reaction

Question 14

what does a negative enthalpy mean?

Answer 14

heat is released during the reaction, exothermic reaction

Question 15

endothermic reaction

Answer 15

absorbs heat energy

Question 16

examples of endothermic reactions:

Answer 16

photosynthesis, cooking, melting

Question 17

what side is the heat energy on in an endothermic reaction?

Answer 17

the reactants side

Question 18

Define the law of conservation of energy

Answer 18

energy is conserved and never created nor destroyed

Question 19

What principle advocates for equilbrium?

Answer 19

Le Chatlier’s Principle

Question 20

61.2 kJ + 2 [A] –> [B]

If we add more of A, which way does it shift and what increases in concentration?

Answer 20

If we add more of A, the energy would shift to the products side and B’s concentration would increase

Question 21

61.2 kJ+ 2 [A] –> [B]

If we decrease the pressure, what way does it shift?

Answer 21

To [A], because the shift in Pressure is based on moles, and A needs to have more moles

Question 22

61.2 kJ+ 2 [A] –> [B]

If we increase the temperature, what substance increases?

Answer 22

[B], because the kJ is on the reactants side and it needs to shift to products side

Question 23

During phase changes, what happens to the temperature?

Answer 23

Stays constant

Question 24

What happens to the energy when breaking bonds?

Answer 24

Energy supplied/absorbed

Question 25

What happens to the energy when forming bonds?

Answer 25

Energy released

Question 26

What is chemical potential energy?

Answer 26

The energy stored in the chemical bonds of a substance.

Question 27

Where is the temperature changing in a heating curve?

Answer 27

The diagonal lines: /

Question 28

What do heating curves show?

Answer 28

Shows how a substance's temperature changes as heat is added and displaying phase changes

Question 29

what's the symbol for enthalpy?

Answer 29

delta H

Question 30

How do you calculate the heat energy absorbed in a phase change in a heating curve?

Answer 30

q= n (moles) times enthalpy of fusion (delta H fus)

Question 31

Where are the phases changing in a heating curve?

Answer 31

The flat lines : ---

Question 32

The 1st flat line is equal to ? :

Answer 32

The enthalpy of fusion

Question 33

The 2nd flat line is equal to ? :

Answer 33

The enthalpy of vaporization

Question 34

How do you calculate the heat energy absorbed in a phase change (ex: ice going to liquid water) from a heating curve?

Answer 34

Divide the enthalpy of vaporization by the enthalpy of fusion.

Question 35

Kinetic Energy and temperature's relationship?:

Answer 35

Direct

Question 36

What happens in segments 1,3, and 5?

Answer 36

The kinetic energy is increasing

Question 37

What happens in segments 2 and 4 in relation to energy?

Answer 37

The potential energy is increasing

Question 38

How do you calculate the heat energy absorbed in segments 1,3, and 5?

Answer 38

Use q=mCdeltaT

Question 39

What's a phase diagram show?

Answer 39

The different states of matter and when they transition according to temperature and pressure

Question 40

What is entropy?

Answer 40

A measure of the disorder of a system

Question 41

Example of entropy

Answer 41

A campfire

Question 42

How do you calculate the enthalpy change from products and reactants?

Answer 42

Sum of enthalpies of the product-sum of enthalpies of the reactants or use q=mCdeltaT

Question 43

Definition of boiling

Answer 43

the process by which a liquid turns into a vapor when it is heated to its boiling point

Question 44

Definition of evaporation

Answer 44

Liquid->Gas NOT at boiling point at the surface of a liquid

Question 45

Definition of vaporization

Answer 45

Liquid->Gas AT boiling point

Question 46

More temp. and pressure required to break bonds=?

Answer 46

Stronger bonds

Question 47

Sublimation

Answer 47

solid->gas

Question 48

condensation

Answer 48

gas->liquid

Question 49

deposition

Answer 49

gas->solid

Question 50

when to use delta H fusion formula?

Answer 50

when there is a phase change

Question 51

when to use delta H vaporization formula?

Answer 51

Vaporize substance (liquid->gas)

Question 52

A higher temperature with the same volume=

Answer 52

Higher entropy

Question 53

What 4 factors affect reaction rate?

Answer 53

Presence of a catalyst, concentration, temperature, surface area

Question 54

What happens when you add a catalyst to a reaction?

Answer 54

Speeds up the reaction rate and it increases the activation energy

Question 55

What happens when you increase the temperature in a reaction?

Answer 55

The reaction rate increases as the number of effective collisions increases.

Question 56

Which combination of positive/negative delta S and delta H favors a spontaneous reaction?

Answer 56

Positive delta S, negative delta H

Question 57

thermochemistry

Answer 57

the study of the transfers of energy as heat that accompany chemical reactions and physicals changes

Question 58

what is an activated complex

Answer 58

a transitional structure that results from an effective collision that persists while old bonds are breaking and new bonds are forming