Chem 272 Exam 2

Front 1

How does pressure change with altitude

Back 1

Pressure Decreases logarithmically

Front 2

2 main components of the atmosphere

Back 2

N2, O2

Front 3

photodissociation

Back 3

the rupture of a chemical bond due to the absorption of a photon

Front 4

solving for the maximum wavlength necessary to dissociate a molecule. (you are given dissociation value of the molecule)

Back 4

convert the dissociation value to J/Molecule by dividing by Avagadro's # (6.022E23)

Next calculate the frequency of the wavelength by using E=hv (v=E/h) h is 6.626E-34

calculate the wavenlength by using the equation wavelength=c/v (c= 3E8)

convert to nm by multiplying by 1E9

Front 5

photodissocation of N2 occurs

Back 5

not readily

Front 6

How does Ozone form

Back 6

collisons between O2 and O molecules

Front 7

How does Ozone get rid of its excess energy

Back 7

by colliding with other molecules:

O3* + M --> O3 + M*

Front 8

where does the highest rate of O3 formation occur, and why

Back 8

near the stratopause, because the formation of Ozone requires the presence of O atoms, and at low altiudes, the photons that contain the eenrgy to dissocaite O2 to O have already been absorbed. Also, you need collisions between O2 an O to occur, and the concentration of these molecules is greater at lower altitudes.

Front 9

CFC's

Back 9

when CFC's diffuse into the stratosphere, they are exposed to high energy radiation, which breaks apart the C-Cl bonds but not the C-F bonds because C-Cl bonds are much weaker. Chlorine reacts with Ozone in a cycle which ends with the formation of O2

2O3 + Cl --> 3O2

Front 10

CFC's replaced by

Back 10

Hydroflourocarbons, HFC's

Front 11

How does sulfur contribute to acid rain

Back 11

SO3 + H2O --> H2SO4

Sulfur from coal burning reacts with water vapor to produce sulfuric acid

Front 12

Lowest pH sustainable to vertebrates, and most invertebrates

Back 12

4

Front 13

pH value of Acid rain

Back 13

4

Front 14

How does CO work

Back 14

binds to iron in hemoglobin, causing the hemoglobin to no longer be able to bind oxygen.

Only takes very small amounts because the equilibrium binding constant for CO is 210 times greater than O2.

Front 15

Main components of greenhouse effect

Back 15

H20 (water vapor), and CO2, they trap the radiation emitted from the Earths surface, thus keeping the earth warm.

Front 16

Desalination of seawater

Back 16

Reverse Osmosis- Mechanical pressure is applied to an impure solution to force pure water through a semi-permeable membrane. The term is reverse osmosis, because normal osmosis would result in pure water moving in the other direction to dilute the impurities

Front 17

global dimming

Back 17

lessening of the ifrared radiation hitting the earths surface.. caused by SO2, causing cooling of the earth and masks effect of increased greenhouse gasses

Front 18

S

Back 18

Entropy, measure of disorder

Front 19

H

Back 19

Enthalpy, Heat content or total heat

Front 20

G

Back 20

free energy, G=H-TS

Front 21

∆G⁰

Back 21

∆G⁰=-RTln(Keq)

Front 22

spontaneous process

Back 22

occurs on its own, w/o external assistance

moves rxn to equilibrium

occurs only for certain T&P often times

Front 23

exothermic rxn's

Back 23

temperature increses

Front 24

endothermic rxn's

Back 24

temperature decreases

Front 25

Generally ∆S =

Back 25

∆S = qrev/T

Front 26

For phase changes ∆S =

Back 26

∆Hfusion/T

Front 27

For isothermal expansion of an ideal gas, ∆S =

Back 27

nRln(V2/V1)

Front 28

The normal boiling point of ethanol is 78.3 C, and its molar enthalpy of vaporization is 38.56 kJ/mol. What is the change in entropy in the system (∆S) when 68.3 g of ethanol at 1 atm condenses to liquid at the normal boiling point?

Back 28

PG 819 -163J/K

Front 29

2nd Law of Thermodynamics

Back 29

any irreversible process results in an overall increase in entropy, whereas a reversible process results in no overall change in entropy.

Front 30

Boltzmann's Equation

Back 30

S = k ln W

S = k ln Wfinal
------
Winitial

Front 31

What is 'W' in boltzmanns equation

Back 31

microstate = snapshot of the position and speeds of all the molecules in a system at a particular moment in time

Front 32

# of microstates increases with:

Back 32

vol, temp, # of independently moving particles

Front 33

entropy of a system increases when

Back 33

gasses are formed from either solids of liquids

liquids or solution