4.1-4.3: Nitrogen Oxides, Ozone, and Gasoline:

Question 1

controlling factor (in chemistry of atmosphere/earth’s crust)

Answer 1

reactivity of oxygen

Question 2

oxygen is avid for…

Answer 2

electrons (e-)

Question 3

oxygen has the __ electronegativity

Answer 3

2nd highest
- (behind fluorine)

Question 4

(oxygen) + (most elements) =

Answer 4

stable oxides

Question 5

in Earth’s Crust = oxygen + _____ = oxides

Answer 5

Fe, Al, M, Ca, C, Si

Question 6

in the ocean = oxygen + _____ = oxide

Answer 6

hydrogen

Question 7

in the atmosphere = oxygen + ___ = oxides

Answer 7

CO2 and SO2

Question 8

CO2 and SO2 oxides ( and nitrogen oxides) are…

Answer 8

highly volatile

Question 9

Trends in atmospheric oxides are based on…

Answer 9

standard enthalpies & free energies of formation

Question 10

Standard enthalpy

Answer 10

heat released/absorbed under standard conditions when compound is formed

Question 11

exothermic

Answer 11

(-) = heat released

Question 12

most molecules are…

Answer 12

exothermic

Question 13

endothermic

Answer 13

(+) = heat absorbed

Question 14

NO, NO2, O3 are all ___ molecules so…

Answer 14

endothermic
- free energy = (+)

Question 15

standard conditions

Answer 15

• T = 25°C
• P = 1 atm

Question 16

free energy is almost always __ and favors ___

Answer 16

(-) –> favors product formation at equilibrium

Question 17

Free energy change =

Answer 17

ΔG = -RTln(Keq)

Question 18

Keq =

Answer 18

equilibrium constant = ([products]^(# of molecules in reaction) ) /([reactants]^(# of molecules in reaction))

Question 19

R =

Answer 19

gas constant = 0.008314 kJ K-1

Question 20

T =

Answer 20

absolute temp = °K

Question 21

Reaction ↑ heat =

Answer 21

favors product formation
- Equilibrium = shifted right

Question 22

Standard thermodynamic equation for free energy =

Answer 22

ΔG = ΔH – TΔS

Question 23

↓ temp =

Answer 23

reverse reaction (spontaneously)

Question 24

Outside combustion zone, NO =

Answer 24

unstable = decomposition slows down

Question 25

how are rates of reaction affected by temp?

Answer 25

↑ temp = ↑ rate of reaction

Question 26

ΔG =

Answer 26

Δ in standard free energy of a reaction

Question 27

hygroscopic

Answer 27

absorbed in rain-drops and rained into atmosphere

Question 28

hygroscopic effect on NOx

Answer 28

Removes NOx molecules from atmosphere

Question 29

Activation energy

Answer 29

kinetic barrier reaction must be overcome by energy input

Question 30

Activation energy and free energy = dependent on ____

Answer 30

chemical and mechanism

Question 31

gas-phase reactions are slow bc…

Answer 31

they require a higher activation energy

Question 32

example of a mechanism for reaction

Answer 32

breaking reactant bonds, increasing temperature

Question 33

Free radicals

Answer 33

involved in mechanisms for reactions (ex: HO⦁)

Question 34

Hydroxyl radicals (HO⦁)

Answer 34

mechanism for atmospheric oxidation

Question 35

How does the free energy of a reaction differ from the enthalpy of a reaction?

Answer 35

• Free energy- total energy available for thermodynamic work (enthalpy + entropy)
• Enthalpy- total energy of system that can be converted to heat

Question 36

What does it mean when a free energy change is positive or negative?

Answer 36

(-) = releases energy ≠ energy input
- spontaneous
(+) = requires energy = energy input
- non-spontaneous

Question 37

What is the relationship between the free energy change of a reaction and its equilibrium constant?

Answer 37

= inverse relationship
- ΔG = (+) –> Keq = (-)
- ΔG = (-) –> Keq = (+)

Question 38

Reaction @ equilibrium: free energy =

Answer 38

0

Question 39

What are the natural and anthropogenic sources of NO in the atmosphere?

Answer 39

• Natural: volcanoes, oceans, biological decay, lightning, microbial sources
• Anthropogenic: fossil fuel combustion, biomass burning, oxidation of ammonia

Question 40

(-) enthalpy =

Answer 40

exothermic = heat released

Question 41

(+) enthalpy =

Answer 41

endothermic = heat absorbed