Atmosphere

Question 1

Explain what is meant by the term dynamic equilibrium.

Answer 1

The rate of forward reaction = rate of back reaction
and the concentrations of reactants and products remain
in a closed system

Question 2

Give industrial activities that acts as a source of atmospheric carbon dioxide

Answer 2

Refining oil
Generating electricity
Processes in a petrochemical plant
Producing steel / iron
Heating limestone

Question 3

Name a gas other than CO2 that is present in vehicle exhaust fumes, which is a pollutant. Explain why it is considered to have a polluting effect

Answer 3

Nitrogen oxides which cause acid rain

Question 4

CO2 is described as a ‘Greenhouse gas’. Explain how increased concentrations of CO2 in the troposphere could be linked to global warming, saying where the energy comes from originally.

Answer 4

UV from the sun is absorbed by the Earth. The Earth than radiates IR back out. CO2 in the troposphere absorbs IR which causes their bonds to vibrate more. The more CO2 the more radiation absorbed

Question 5

Name two ways of reducing the amount of carbon dioxide in the atmosphere, other than
storing it under the ocean.

Answer 5

Burn less fossil fuel and plant more trees

Question 6

Suggest why carbon capture is expensive

Answer 6

Require a lot of equipment and energy

Question 7

Explain why nanoparticles are better catalysts than powered solids

Answer 7

They have a arguer surface area to volume ratio so there will be more collisions per hit of time

Question 8

explain what is meant by the term activation enthalpy

Answer 8

The minimum energy for colliding particles to react

Question 9

Describe and explain the effect of increasing pressure on the equilibrium yield of areaction

Answer 9

The yield will decrease if it has more moles than the reactants

Question 10

Give an agricultural activity that acts as a source of methane

Answer 10

Growing rice / livestock farming / making silage

Question 11

Explain how increased concentrations of methane in the troposphere could be linked to global warming

Answer 11

More methane means more IR radiation and this energy in transferred into kinetic energy which warms the atmosphere

Question 12

Bromomethane and chloromethane are both present in the atmosphere. Explain how chloromethane causes ozone depletion in the stratosphere and suggest why bromomethane has a lower ozone depleting potential than chloromethane.

Answer 12

The C-Cl is too strong to be broken down the troposphere but I’d broken down in then stratosphere by photodissocition caused for high energy uv producing chlorine radicals that catalyse the breakdown of ozone. C-Br is weaker so is broken down in the troposphere

Question 13

Explain how CO2 absorbing IR can result in the warming of the atmosphere

Answer 13

The molecules re-emit IR in all directions

Question 14

Disadvantages to capture and storage

Answer 14

Requires lots of energy

Costly due to clearance of land and the new infrastructure

Question 15

Explain why the formation of ozone takes place in the stratosphere but not the troposphere

Answer 15

Uv is only present the stratosphere. This high frequency radiation is what is needed to form O radicals

Question 16

Explain why it’s important that there is a certain minimum amount of ozone in the stratosphere

Answer 16

It absorbs high energy up which could cause skin cancer

Question 17

Give an industrial activity that acts as a source of atmospheric carbon dioxide, other than burning fuel

Answer 17

refining oil / generating electricity / processes in a

petrochemical plant / producing steel / heating limestone /fermentation

Question 18

what effect does unburnt hydrocarbons have on the environment

Answer 18

Causes smog

Question 19

How is CO introduced into the atmosphere

Answer 19

incomplete combustion of hyndrocarbons

Question 20

2 reasons why CO is classed as a polluting gas

Answer 20

toxic and causes photochemical smog

Question 21

Name the type of bond breaking that occurs to for hyrdoxyl radicals from water

Answer 21

homolytic fission

Question 22

Explain the difference in structure of CO2 and SiO2 and why this results in them being different states

Answer 22

CO2 is a simple molecule
SiO2 has a giant covalent
O2 has weaker intermolecular bonds so requires less energy to separate the molecules

Question 23

Explain the source of IR absorbed by CO2 and the possible link between increased concentrations of CO2 in the troposphere and global warming

Answer 23

The sun emits UV and the Earth absorbs some of this energy and remits it as IR. The CO2 then absorbs the IR making its bonds vibrate more. Some of this kinetic energy is transferred into heat energy so the more CO2 equals more radiation being absorbed

Question 24

Suggest methods for the disposal of CO2

Answer 24

React the CO2 with lime
Disposal in an old mine / old oil or gas well / other suitable disposal site
Pump it / bury it under the ocean

Question 25

which elements can form hydrogen bonds

Answer 25

nitrogen, fluorine and oxygen

Question 26

Why is C-Cl more polar than C-Br

Answer 26

C-Cl is more elctronegative

Question 27

Describe the theoretical work and research that led to the discovery ozone depletion stratosphere and why the evidence was originally overlooked

Answer 27

Discovery that Cl and affect ozone
Spectroscopic measurements showed ozone levels depleted
They were overlooked because they were so low

Question 28

Natural process that causes ozone breakdown

Answer 28

Photodissocition of o3 to for o and o2