Ozone Story - Radicals Flashcards Preview

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Flashcards in Ozone Story - Radicals Deck (40)
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1
Q
A
2
Q

What is the troposphere?

A

the lower layer of the atmosphere

3
Q

What is the stratosphere?

A

the upper layer of the atmosphere, 15km above sea level

4
Q

Why doesn’t nitrogen absorb radiation well?

A

it has a very strong triple bond that requires a lot of energy to make it vibrate

5
Q

How do you convert between ppm and % of the atmosphere?

A

ppm -> %

x 10,000

6
Q

What is ppm?

A

particles per million

unit of measuring how much of a gas is present

7
Q

What are the 4 effects that radiation can cause in molecules?

A

Electronic energy

Vibrational energy

Rotational energy

Translational energy

8
Q

Which type of radiation causes electronic energy in molecules?

A

UV / visible light

9
Q

Which type of radiation causes vibrational energy levels?

A

infrared radiation

10
Q

Which type of radiation causes rotational energy levels in molecules?

A

microwaves

11
Q

Which type of radiation causes translational energy levels in molecules?

A

microwave / radio

12
Q

What is electronic energy?

A

energy that affects the electrons only

13
Q

What is vibrational energy?

A

energy that causes the bonds to vibrate

14
Q

What is rotational energy?

A

energy that causes the whole molecule to rotate

15
Q

What is translational energy?

A

energy that causes the whole molecule to move around

16
Q

Does exciting electrons require more or less energy than moving a molecule as a whole?

A

significantly more

17
Q

What happens to halogens in the stratosphere?

A

they are ionised by UV radiation and the diatomic molecules are split into radicals

18
Q

What is a radical?

A

a chemical with an unpaired electron

19
Q

What is the general reactivity of radicals?

A

they tend to be reactive

20
Q

What is homolytic bond fission?

A

Breaking a bond equally, so each molecule recieves an equal number of electrons

21
Q

How are photons commonly represented in atmospheric chemistry?

A

22
Q

What is heterolytic bond fission?

A

breaking a bond unequally

23
Q

What is the reaction for Bromine undergoing homolytic bond fission?

A
24
Q

What is the reaction for a compound undergoing heterolytic bond fission?

A
27
Q

What is photochemical dissociation?

A

the reaction where a chemical is broken down by a photon

28
Q

What are the 2 reactions that show the formation of Ozone?

A

O2 -> O. + O.

O. + O2 -> O3

29
Q

What 3 things can happen to an oxygen radical after being dissociated?

A

react with O2 to form ozone

react with another oxygen radical to form O2

react with ozone to form 2O2

30
Q

What is the most likely reaction an oxygen radical will undergo and why?

A

react with O2 to form ozone

there is a majority of O2 compared to oxygen radicals or ozone, so it is more likely to collide with the O2

31
Q

Is the formation of ozone endothermic or exothermic?

A

exothermic

32
Q

What is the reaction for the decomposition of ozone?

A

O3 -> O2 + O.

33
Q

What is the initiation step in the radical chain reaction for hydrogen halides?

A

X2 + hν -> 2X.

34
Q

What are the propogation steps for the chain reaction of hydrogen halides?

A

X. + H2 -> HX + H.

H. + X2 -> HX + X.

35
Q

What are the termination steps for the chain reaction of hydrogen halides?

A

H. + H. -> H2

X. + X. -> X2

H. + X. -> HX

36
Q

What is the overall effect of the radical chain reaction between hydrogen and a halogen?

A

H2 + X2 -> 2HX

37
Q

What is a termination reaction?

A

any reaction where 2 radicals react, resulting in products with no radicals

38
Q

What is the initiation step for the radical chain reaction between a halogen and methane?

A

X2 + hν -> 2X.

39
Q

What are the propogation steps for the radical chain reaction between methane and a halogen?

A

X. + CH4 -> HX + CH3.

CH3. + X2 -> CH3X + X.

40
Q

What are the termination steps for the radical chain reaction between methane and a halogen?

A

X. + X. -> X2

CH3. + X. -> CH3X

CH3. + CH3. -> C2H6

41
Q

How can ozone be removed from the atmosphere?

A

radicals in general but particularly:

Br

Cl

OH-

NO

42
Q

What is the chain reaction for the removal of ozone with a radical?

A

X = Cl, Br, NO or OH-:

X. + O3 -> XO + O2

XO + O. -> X. + O2

O. + O3 -> 2O2