Mcat Chemistry Lecture 3

Front 1

____ - the study of energy and its relationship to macroscopic properties of systems

Back 1

Thermodynamics

Front 2

Thermodynamic functions are based on ____

Back 2

probabilities

Front 3

____ - macroscopic body under study

Back 3

Systems

Front 4

____ - both energy and mass are exchanged -ex. ____

Back 4

Open system
fluid flow through a pipe

Front 5

____ - exchanges energy but not mass - ex. ____

Back 5

Closed system
push a block on a plane or radiator

Front 6

____ - no mass or energy can be transferred to or from the system ex. ____

Back 6

Isolated system
the universe

Front 7

____ - energy is conserved/energy of an isolated system is conserved

Back 7

First law of thermodynamics

Front 8

restate for a closed system - they change of energy in a closed system is the sum of the heat transferred into the system and the work done on the system: ____

Back 8

ΔE = Q+W

Front 9

____: the energy transferred from a hot body to a cold body via a natural process

Back 9

Heat

Front 10

____: energy transferred due to a force

Back 10

Work

Front 11

3 types of heat transfer: ____

Back 11

conduction
convection
radiation

Front 12

____ - taking an entire group of molecules and their energy and carrying them to another place, (moving hot air or cold water around)

Back 12

Convection

Front 13

____ - loses heat by emanating electromagnetic waves

Back 13

Radiation

Front 14

____ is energy transferred via molecular collisions, it requires direct physical contact

Back 14

Conduction

Front 15

Conduction of heat through a metal bar is like fluid through a pipe, it ____ as the cross sectional area _____ and as the temperature ____ and ____ as the length of the bar ____

Back 15

increases
increases
increases
decreases
increases

Front 16

____, heat conduction, and ____ are all the same qualitatively

Back 16

fluids
electricity

Front 17

Lose heat ____ to surface area and temperature to the 4th power (in Kelvin's)
But! Environment also ____ into you, depending on temperature ____ between you and environment

Back 17

proportional
radiates
difference

Front 18

____ - A system at rest can do pressure/volume work, PV work.

Back 18

Work

Front 19

At constant pressure just P times V, if no volume change than no ___ is done.

Back 19

PV work

Front 20

____
Thermal energy cannot be completely converted to work in a cyclical process;
In some point in a perpetual process some energy must become unavailable to ever do work again.

Back 20

2nd law of thermodynamics -

Front 21

Thermo state functions (7) - describe a thermodynamic state, describe a state not a process

Back 21

VEGIE TP
Internal energy
Temperature
Volume
Pressure
Enthalpy
Entropy
Gibbs Energy

Front 22

____ - all the possible molecular energies on a microscopic level, there are 6 three thermal energies and three others (thermals are rotational, vibrational, and translational
Three others are: intermolecular potential, electronic and rest mass)

Back 22

Internal energy

Front 23

Mcat, Heat energy = ____ = ____ = ____

Back 23

heat
thermal energy
internal energy

Front 24

____ of a substance is the average measurement of its kinetic energy of its molecules

Back 24

Temperature

Front 25

____ - temp is directly proportional to the translational energy of its molecules

Back 25

Fluid substance

Front 26

____ directly proportional to the vibrational energy of its molecules as long as it is not at a very low temperature

Back 26

Solid substance

Front 27

____ = higher temperature, temperature in Kelvin's or degrees Celsius

Back 27

Faster movement

Front 28

____ is coldest possible where vibration is at a minimum but still occurs.

Back 28

0 Kelvin

Front 29

____ - absolute 0 Kelvin cannot be achieved.

Back 29

3rd law of thermodynamics

Front 30

Enthalpy =

Back 30

Internal energy + PressureVolume
H = U + PV

Front 31

Standard state is not!!!

Back 31

STP

Front 32

The degree mark indicates ____

Back 32

standard state at 25 degrees.

Front 33

SO, for condensed phases, liquids/solids change in ____ = heat which is approximately equal to change in ____

Back 33

enthalpy
internal energy

Front 34

ΔHf° =

Back 34

enthalpy of formation

Front 35

Standard state for liquid/solid is ____, for a gas ____ and it must behave as an ____.

Back 35

1 bar
1 bar
ideal gas

Front 36

For a solution standard state is ____.

Back 36

1 molar concentration.

Front 37

Elements in their natural state are assigned an enthalpy of ____ in their standard state at ____.

Back 37

0
25 degrees C

Front 38

The change of enthalpy of a reaction at standard state equals enthalpy of formation of the ____ minus enthalpy of formation of the ____.

Back 38

products
reactants

Front 39

____- heat exits, I subtract the heat so it is negative

Back 39

Exo

Front 40

____ - heat enters, I add the heat so it is positive.

Back 40

Endo

Front 41

Change of enthalpy is ____ it is exothermic and heat is released

Back 41

negative

Front 42

Change of enthalpy is ____ is it endothermic and heat is absorbed

Back 42

positive

Front 43

____, energy required to break the bonds of the reactants, the energy required to achieve the transition state

Back 43

Activation energy

Front 44

The ____ is at the top of the hill and cannot be isolated.

Back 44

transition state

Front 45

The ____ is at a valley and it can be isolated

Back 45

intermediate

Front 46

If you look at diagram from right to left the distance from bottom of the hill to top that is the ____ for the reverse reaction.

Back 46

activation energy

Front 47

The change in _____, _____ or ____ is the net distance between the reactants and products that is the bottoms of the two little hills.

Back 47

energy
enthalpy
gibbs energy

Front 48

A ____ does not ever change this, it only changes the activation energy for the forward or reverse reaction (increases it by lowers the hill.)

Back 48

catalyst

Front 49

____ = natures tendency toward disorder.

Back 49

Entropy

Front 50

A ____ that is designated to be 0 for a pure substance at absolute 0 Kelvin.

Back 50

state function (entropy)

Front 51

____ is natures way of creating the most probable state.

Back 51

Entropy

Front 52

Tendency to favor the most probable state.

Back 52

Entropy

Front 53

This is another way to look at the ____, entropy of the universe must increase for any real process

Back 53

2nd law of thermodynamics

Front 54

(millions of molecules between 2 bottles, most likely ____ of the molecules in each bottle)

Back 54

roughly half

Front 55

Cannot apply thermodynamic properties to microscopic principles.
Cannot look at a small portion of the system.

Back 55

entropy

Front 56

____ - reversible process happens at equilibrium = no change in entropy

Back 56

Quasistatic process

Front 57

Entropy increases with ____.

Back 57

temperature
number
volume

Front 58

In a reversible process is ____ which is the heat transferred divided by the temperature. (kelvins)

Back 58

Δs = Q/T

Front 59

____ = Δs Universe
____ is greater than or equal to 0
Δs Is the change in ____

Back 59

Δs System + Δs Surroundings
Δs Universe
enthalpy

Front 60

Change in ____ is the maximum amount available to do non pv work

Back 60

gibbs free energy

Front 61

____ - Available to do non-pressure-volume work

Back 61

Gibbs free energy

Front 62

Gibbs energy is another ____ where we are interested in the change as opposed to the absolute value.

Back 62

state function

Front 63

The formula for the change in Gibbs free energy is

Back 63

ΔG = ΔH - TΔs
G is gibbs free energy
H is enthalpy
T is temperature
S is entropy
All of the changes refer to changes in the system and not! The surroundings

Front 64

If ΔG is negative for a reaction the reaction is ____.

Back 64

spontaneous

Front 65

____ = reaction starts to happen immediately, but might does not say the speed.

Back 65

Spontaneous

Front 66

Exothermic rxn that increases entropy is always ____

Back 66

spontaneous

Front 67

Endothermic rxn that decreases entropy is always ____

Back 67

nonspontaneous

Front 68

High temperature check entropy if it is positive it will probably be ____ if it is negative probably will be ____

Back 68

spontaneous
nonspontaneous