Mcat Chemistry Lecture 5

Front 1

____ phase is a separate phase from liquid water

Back 1

Aqueous

Front 2

Systems may have several ____ and ____ phases, but typically only one ____ phase exists for a given system

Back 2

liquid
solid
gas

Front 3

____ - A measure of the energy necessary to change the temperature of the substance in a given phase by 1 degree Celsius

Back 3

Heat capacity

Front 4

____ is a process the transfer of energy, a process cannot be stored

Back 4

Heat

Front 5

A process where there is no heat flow is called an ____.`

Back 5

adiabatic process

Front 6

Work is ____, so when gas does work on the surroundings it is transferring energy to the surroundings

Back 6

energy transfer

Front 7

Average kinetic energy = 3/2 RT applies here, the gas gets ____ when the molecules move ____

Back 7

hotter
faster

Front 8

A constant ____ heat capacity is greater than a constant ____ heat capacity (for a gas)

Back 8

pressure
volume

Front 9

For liquids and solids increase in potential energy as the molecules move apart, that is because energy increases when objects that are ____ to each other are ____.

Back 9

attracted
separated

Front 10

C=

Back 10

C= Q/ΔT
C = Heat capacity
Q = heat flow
ΔT = change in temperature
(This formula assumes that all the energy transferred is heat)

Front 11

Work must also be considered as a form of ____

Back 11

energy transfer

Front 12

____ - temperature change expressed per unit mass

Back 12

Specific heat

Front 13

Q=

Back 13

Q= mcΔT
M = mass of the substance
c = the specific heat of the substance

Front 14

____ is for an entire system, specific heat is per mass of a substance
Can even have molar or volume ____ which is heat capacity per mole of per volume

Back 14

Heat capacity
Heat capacity

Front 15

____ will be in units of energy per degree temperature

Back 15

Heat capacity

Front 16

____ will be in energy per gram or kilogram degree Celsius molar heat or volume heat will replace the weight with moles or ml's

Back 16

Specific heat

Front 17

The ____ of water is 1 calorie per gram per degree Celsius.
For ice and steam the ____ is approx 1/2 calories per gram per degree Celsius.

Back 17

Specific heat
Specific heat

Front 18

____ - measures heat flow at constant pressure

Back 18

Coffee cup calorimeter

Front 19

At constant pressure Q = ΔH, ____

Back 19

enthalpy change

Front 20

____ - burn or combust something in a rigid container and measure temp change in the water surrounding the container
The temperature change times the heat capacity of the calorimeter is approximately equal to the ____ of the reaction
Because internal energy change only approximates ____

Back 20

Bomb calorimeter
heat
enthalpy change

Front 21

____ - temp on the y axis and heat on the x axis

Back 21

Heat curve

Front 22

Heat curve
For the first rising segment ____, where c is the specific heat of the solid

Back 22

Q= mcΔT

Front 23

Heat curve
Second line is a flat one where temp does not change, have to use ____, simply have to multiply this by the appropriate amount of substance to find Q
Sometimes the ____ is called the ____ and is represented by a L.

Back 23

enthalpy of fusion
enthalpy of fusion
latent heat of fusion

Front 24

Heat curve
The third segment is a positive slope line this starts once all the solid has melted, this line extends from the melting point to the boiling point, along this line the substance is a liquid, as energy is added the speed of the molecules in the liquid increase, as the speed increases the temperature increases
Again we use the formula ____

Back 24

Q= mcΔT

Front 25

Heat curve
The fourth segment is another flat line beginning at the boiling point. This line represents vaporization. As energy is added the bonds of the liquid are broken creating a gas. The heat of ____ is usually greater than the heat of fusion, because to ____ a substance the intermolecular forces must be completely overcome.

Back 25

vaporization
vaporize

Front 26

Heat of fusion
The fifth segment is a positive slope line going up from the boiling point. This line represents the substance as a gas, as energy is added the speed of the molecules ____ and temperature ____.

Back 26

increases
increases

Front 27

Heat of ____ - solid to gas

Back 27

sublimation

Front 28

Heat of ____ - solid to another solid

Back 28

transition

Front 29

Heat curve
Along the second line - increase in ____, broken bonds more movement, but decrease in ____ - energy is absorbed to break the bonds.

Back 29

entropy
enthalpy

Front 30

____ we see that ΔG may be positive or negative, it could be spontaneous or nonspontaneous
The direction of the rxn depends upon the ____, as we would expect from a phase change.

Back 30

ΔG = ΔH - TΔs
temperature

Front 31

___ compares - pressure on the y-axis to temperature on the x-axis

Back 31

Phase diagram

Front 32

Three area diagram - ____
____ - is up and to the left , because solids exist at high pressure and low temperature
____ - is to the right of the solid - because as temps increase solids melt
____ - lies all along the bottom of the diagram and to the right - because gases exist at low pressures and high temps

Back 32

Phase diagram
solid
liquid
gas

Front 33

Ice melts under ____

Back 33

pressure

Front 34

Gas to liquid -
Liquid to gas -
Solid to gas -
Gas to solid -
Solid to liquid -
Liquid to solid -

Back 34

condensation
vaporization
sublimation
deposition
melting
freezing

Front 35

phase diagrams
The lines represent temp and pressure values where the phases exist in ____

Back 35

equilibrium

Front 36

phase diagram
____ - where all three lines meet, all three phases exist in equilibrium only at this point.

Back 36

Triple point

Front 37

phase diagram
____ - end of the gas/liquid line, it is determined by the critical temp and critical pressure, above the ____ gas and liquid cannot be distinguished from one another, they have the same density The substance above this point is called a ____.

Back 37

Critical point
Critical point
supercritical fluid

Front 38

____ - depend on number not kind

Back 38

Colligative properties

Front 39

The property depends not on what type but how many you have.

Back 39

Colligative properties

Front 40

4 important colligative properties -

Back 40

VFBO
Vapor pressure - more nonvolatile solute you add to the solution the lower the vapor pressure
Boiling point - nonvolatile solute raises the boiling point (because of lowered vapor pressure)
Freezing point
Osmotic pressure

Front 41

Boiling occurs when the vapor pressure equals the atmospheric pressure
____

Back 41

ΔT = KMI
K is the boiling point elevation constant of the volatile solvent
M is the molality of the solution
I is the vant hoff factor (the number of pieces each solute will break into when placed into solution, NaCl will break into 2 pieces for every mole added in water so theoretical vant hoff is 2, glucose dissolves but does not break down so theoretical would be 1)

Front 42

Freezing - stuff freezes when it forms symmetrical structures, impurities inhibit symmetrical structures from forming, so adding solute to a liquid lowers the freezing point

Back 42

ΔT = KMI
Only k is the freezing point constant

Front 43

Adding A to pure B will lower the ____
Adding B to pure A will lower the ____
There is some ratio of A to B that has the ____, as a mixture

Back 43

FP of B
FP of A
lowest freezing point

Front 44

____ - is created by solute in solution, can think of it as pulling inward while hydrostatic pressure pushed outward (good enough for the mcat)

Back 44

Osmotic pressure

Front 45

Osmotic pressure
Can also think of it as the solute molecules in solution creating their own pressure so formula:

Back 45

∏ = ImRT
I is the vant hoff factor
Other factors from pv = nrt, only M is molarity

Front 46

Utube w/ the selectively permeable membrane - solvent can move not solute
The difference between the fluid pressures on both sides is the ____
The total pressure on the side w/ the solute is just the ____.

Back 46

osmotic pressure
fluid pressure

Front 47

osmotic pressure
Or can look at it as ____ - pure water is 0, when solute is added to water the potential drops to be negative, like most things water potential flows from high ____ to lower ____

Back 47

osmotic potential
osmotic potential
osmotic potential