Chapter 11 Thermo Chemistry

Front 1

First law of thermodynamics?

Back 1

energy can be converted from one form to another but energy cannot be created or destroyed

Front 2

Potential energy? (PE)

Back 2

due to position or composition

Front 3

Kinetic energy? (KE)

Back 3

due to motion of object

Front 4

Symbol for heat?

Back 4

(q)

Front 5

Heat is the

Back 5

energy transferred between samples because of difference in temperatures

Front 6

Amount of energy transferred is measured in ?

Back 6

Joules (J)

Front 7

Heat _____ be measured ___________ so __________ is used to track transfer of _______

Back 7

cannot, directly, temperature, heat

Front 8

2 ways to transfer energy ?

Back 8

1. heat (q)

2. work (w)

Front 9

Calorimetry is the process of

Back 9

measuring energy changes

Front 10

Calorimetry requires an ____________ system

Back 10

isolated

Front 11

Open system?

Back 11

both matter and energy can enter/escape

Front 12

Closed system?

Back 12

matter cannot but energy can enter/escape

Front 13

Isolated system

Back 13

neither matter nor energy can enter/escape

Front 14

In a calorimeter the energy given off during a reaction equals the

Back 14

energy absorbed by water [qabsorbed = qreleased]

Front 15

symbol for specific heat capacity?

Back 15

(c)

Front 16

symbol for heat capacity?

Back 16

(C)

Front 17

SHC is

Back 17

amount of heat (q) required to raise temp. of 1g of the substance by 1 degree C

Front 18

HC is

Back 18

amount of heat required to raise tmp. of given quantity (m) of substance by 1 degree C

Front 19

Change in temp =

Back 19

Tfinal - Tinitial

Front 20

what is the SHC of water?

Back 20

4.19 J/gC

Front 21

symbol for enthalpy is

Back 21

H

Front 22

enthalpy is

Back 22

heat given off/absorbed during a reaction at constant pressure

Front 23

change in enthalpy =

Back 23

Hproducts - Hreactant

Front 24

Exothermic (5)

Back 24

- (-)

- Hp < Hr

- energy produce IN reaction

- flows OUT of system

- container FEELS HOT

Front 25

Endothermic (5)

Back 25

- (+)

- Hp > Hr

- energy CONSUMED by reaction

- flows INTO system

- container FEELS COLD

Front 26

change in enthalpy =

Back 26

heat supplied

Front 27

RC IS

Back 27

reaction coordinate // time

Front 28

characteristics of exothermic reactions

Back 28

- energy produced in reaction

- flows OUT of system

- container feels HOT to touch

Front 29

characteristics of endothermic reactions

Back 29

- energy consumed by reaction

- flows INTO system

- container feels COLD

Front 30

molar enthalpy

Back 30

enthalpy change in chemical system per mole of specified chemical under change

Front 31

change in enthalpy of system is equal to

Back 31

change in thermal energy of the calorimeter

Front 32

4 WAYS OF COMMUNICATING ENERGY CHANGES

Back 32

1. MOLAR ENTHALPY

2. ENTHALPY CHANGE

3. TERM IN BALANCED EQUATION

4. CHEMICAL POTENTIAL ENERGY DIAGRAM

Front 33

METHOD 1

Back 33

Molar Enthalpy

EXO: Delta r H m < 0
ENDO: Delta r H m > 0

Front 34

METHOD 2

Back 34

Enthalpy Change

EXO: reactants -> products; delta r H < 0

ENDO: reactants -> products delta r H > 0

Front 35

METHOD 3

Back 35

Term in Balanced Equation

EXO: reactants -> products + energy

ENDO: reactants + energy -> products

Front 36

METHOD 4

Back 36

Chemical Potential Energy Diagram

EXO: Ep (reactants) > Ep (products)

ENDO: Ep (reactants) < Ep (products)

Front 37

LABEL Q=mc🔺t

Back 37

Q= energy/heat

m= mass

C= Specific heat capacity

t=temp change

Front 38

Label Q = c🔺t

Back 38

Q = energy/heat

c= heat capacity

t= temperature change

Front 39

mass in Q=mc(delta)t can also be

Back 39

Volume

Front 40

Q system =

Back 40

- Q surroundings

Front 41

(Delta)rH =

Back 41

Q

Front 42

m(system)c(system)🔺t(system)=

Back 42

-(MwCw🔺Tw)

Front 43

(Delta)rH =

Back 43

Q

Front 44

mc(delta)t =

Back 44

n x (delta)rHm

Front 45

(delta)rHm is measure in

Back 45

kJ/mol

Front 46

(Delta)rH is measured in

Back 46

kJ

Front 47

RULES FOR HESS' LAW (5)

Back 47

1. Write net reaction equation, if not given

2. Manipulate the given equations so they will add to yield the net equation

3. Multiply, divide and/or reverse the sign of the enthalpy of reaction

4. cancel and add the remaining reactants and products to yield the new equation

5. Add enthalpy changes to obtain the net enthalpy change

Front 48

Reaction rate depends on (3)

Back 48

1. collision frequency

2. probability or orientation factor

3. activation energy (Ea)

Front 49

making bonds

Back 49

releases energy (exo) `

Front 50

breaking bonds

Back 50

absorbs energy (endo)

Front 51

bond formation

Back 51

(-BDE) releases energy (exo)

Front 52

bond breaking

Back 52

(BDE) requires energy (endo)

Front 53

homogenous catalyst

Back 53

catalyst works by increasing chances that 2 molecules will positioned in the right way for a reaction to occur

Front 54

heterozygous catalyst

Back 54

First step: absorption (binding of reactant molecules to catalyst surface)

Front 55

catalytic converter

Back 55

promotes combustion using catalyst

GOAL: to release N2, O2, CO2

Front 56

some calorimetry assumptions

Back 56

1. all energy lost or gained by the chemical system is gained or lost respectively by the calorimeter (total system is isolated)

2. all the material of the system is conserves; that is, the total system is isolated

3. the specific heat capacity of water is 4.19J/gC

4. the thermal energy gained or lost by the rest of the calorimeter (other than water) is negligible, that is, the container, lid, thermometer, and stirrer do not gain or lose thermal energy

Front 57

1mL =

Back 57

1g

Front 58

Combustion is a __________ reaction

Back 58

exothermic