KERBOODLE SUMMARY QUESTIONS: OZ Flashcards
State the main gases in unpolluted air
nitrogen
oxygen
argon
State three human activities that add gases to the air
combustion of hydrocarbons
deforestation
cattle farming
landfill
changes in land use
Calculate how many parts per million by volume of argon (1%) are in a typical sample of tropospheric air.
10 000ppm
Calculate the percentage of neon (18.2ppm) in a typical sample of tropospheric air
0.00182%
Calculate the volume of methane present in 1 dm3 of tropospheric air
concentration of methane in tropospheric air (1.8 ppm)
1.8 x 10-6 dm3
Calculate the percentage of methane molecules in a sample of 1 dm3 of air
concentration of methane in tropospheric air (1.8 ppm)
0.00018%
A beam of infrared radiation has an energy of 3.65 x 10-20 J per photon.
Calculate the frequency of the radiation
5.5 x 1013 Hz
A beam of X-rays has a frequency of 2.60 x 1017 s-1
Calculate the wavelength of the X-rays
1.15 x 10-9 m
Carbon dioxide is a greenhouse gas. It absorbs some of the infrared radiation given off from the Earth’s surface.
Explain why carbon dioxide molecules absorb only certain frequencies of infrared radiation
Specific frequencies corresponding to transitions between vibrational energy levels, making the bonds vibrate more
Carbon dioxide is a greenhouse gas. It absorbs some of the infrared radiation given off from the Earth’s surface.
Explain why absorbing infrared radiation makes the atmosphere warmer
Molecules which have absorbed radiation have more kinetic energy. This energy is subsequently transferred to other molecules in the air by collisions
To change 1 mole of molecular HCl from the lowest vibrational energy level (ground state) to the next vibrational level requires 32.7 kJ
Calculate the energy, in joules, gained by one molecule of HCl when energy is absorbed in this way
[Avagadro constant, NA = 6.02 x 1023 mol-1
Then calculate the corresponding frequencing of radiation. State the type of radiation this corresponds to.
Then calculate the wavelength of this radiation in metres.
- 43 x 10-20 J
- 20 x 10-13 Hz, infrared
- 66 x 10-6 m
You want to heat up a cup of coffee in a microwave cooker.
The cooker uses radiation of frequency 2.45 x 109 Hz
The cup contains 150 cm3 of coffee, which is mainly water.
Calculate the energy needed to raise the temperature of the water by 30oC
[specific heat capacity of water = 4.18 J g-1 K-1]
The calculate the energy transferred to the water by each photon of microwave radiation
Then calculate the energy transferred by one mole of photons
Then calculate how many moles of photons are needed to supply the energy calculated to raise the temperature of water by 30oC
- 88 x 104 J
- 62 x 10-24 J
- 978 J
19 200 moles
State whether or not the species F is a radical
yes
State whether or not the species Ar is a radical
no
State whether or not the species H2O is a radical
no
State whether or not the species OH is a radical
yes
State whether or not the species NO2 is a radical
yes
State whether or not the species CH3 is a radical
yes
The hydroxyl radical, HO•, is an important species in atmospheric chemistry. Reaction A shows one process in which HO• is produced. The reaction is brought about by radiation with a wavelength below 190nm.
Reaction A: H2O + hv –> H• + HO•
Hydroxyl radicals are very reactive and act as scavengers in the atmosphere. One set of reactions which involve stratospheric ozone is:
- *Reaction B:** HO• + O3 –> HO2• + O2
- *Reaction C:** HO2• + O3 –> HO• + 2O2
State whether reaction A is a homolytic or a heterolytic process
homolytic
The hydroxyl radical, HO•, is an important species in atmospheric chemistry. Reaction A shows one process in which HO• is produced. The reaction is brought about by radiation with a wavelength below 190nm.
Reaction A: H2O + hv –> H• + HO•
Hydroxyl radicals are very reactive and act as scavengers in the atmosphere. One set of reactions which involve stratospheric ozone is:
- *Reaction B:** HO• + O3 –> HO2• + O2
- *Reaction C:** HO2• + O3 –> HO• + 2O2
Explain whether reactions A, B and C are initiation, propagation or termination
A is initiation
B and C are propagation
The hydroxyl radical, HO•, is an important species in atmospheric chemistry. Reaction A shows one process in which HO• is produced. The reaction is brought about by radiation with a wavelength below 190nm.
Reaction A: H2O + hv –> H• + HO•
Hydroxyl radicals are very reactive and act as scavengers in the atmosphere. One set of reactions which involve stratospheric ozone is:
- *Reaction B:** HO• + O3 –> HO2• + O2
- *Reaction C:** HO2• + O3 –> HO• + 2O2
Write an equation which shows the overall result of reactions B and C
2O3 ⇌ 3O2
The hydroxyl radical, HO•, is an important species in atmospheric chemistry. Reaction A shows one process in which HO• is produced. The reaction is brought about by radiation with a wavelength below 190nm.
Reaction A: H2O + hv –> H• + HO•
Hydroxyl radicals are very reactive and act as scavengers in the atmosphere. One set of reactions which involve stratospheric ozone is:
- *Reaction B:** HO• + O3 –> HO2• + O2
- *Reaction C:** HO2• + O3 –> HO• + 2O2
Write an equation which shows the overall result of reactions B and C
2O3 ⇌ 3O2
The hydroxyl radical, HO•, is an important species in atmospheric chemistry. Reaction A shows one process in which HO• is produced. The reaction is brought about by radiation with a wavelength below 190nm.
Reaction A: H2O + hv –> H• + HO•
Hydroxyl radicals are very reactive and act as scavengers in the atmosphere. One set of reactions which involve stratospheric ozone is:
- *Reaction B:** HO• + O3 –> HO2• + O2
- *Reaction C:** HO2• + O3 –> HO• + 2O2
State the role of HO• in this process
catalyst
The creation of nitrogen monoxide from human activities is of concern because it is thought to lead to a loss of ozone from the stratosphere. Reactions D and E show how this loss can occur.
- Reaction D:** NO• + O3 –> NO2• + O2 ΔH* = -100 kJmol-1
- Reaction E:** NO2• + O –> O2 ΔH* = -192 kJmol-1
State one human activity which leads to the production of a significant amount of NO.
oxidation of nitrogen in internal combustion engines

















