The Atmosphere

Question 1

What percentage of the atmosphere is nitrogen

Answer 1

78%

Question 2

What is the value and units for planks constant?

Answer 2

6.63 x 10-34 J/Hz

Question 3

What formula links plancks constant, frequency and energy

Answer 3

Energy = planck’s constant x frequency of light

Question 4

What are the 4 aspects a molecule behaviour associated with its energy

Answer 4

Translation, rotation, vibration and electronic

Question 5

In terms of a molecules behaviour, what is translation?

Answer 5

The molecule moving around as a whole

Question 6

In terms of a molecules behaviour, what does electronic mean?

Answer 6

The movement of electrons from on energy level to another

Question 7

Rank the energy activities from lowest energy requirement to highest

Answer 7

Translation, rotation, vibration, electronic

Question 8

What part of the light spectrum affects electronic energy changes

Answer 8

Visible and ultra-violet

Question 9

What part of the light spectrum results in rotating a molecule?

Answer 9

Microwave

Question 10

What is the another way of referring to the breaking of bonds?

Answer 10

Bond fission

Question 11

What is homolytic fission

Answer 11

When the electrons shared in a covalent bonds are evenly split between the two atoms resulting in the formation of free radicals

Question 12

What do you call an atom with an unpaired electron

Answer 12

A free radical

Question 13

What is heterolytic fission

Answer 13

When a covalent bond breaks and the electrons all go to one atom, resulting in a negative and positive charged ion

Question 14

Why are free radicals so reactive?

Answer 14

Because filled outset shells are more stable than unfolded one, so they tend to grab electrons from other atoms to fill their outer energy level

Question 15

What is the first stage of a free radical reaction called and how do you recognise one

Answer 15

Initiation, and usually a photodissocition reaction occurs resulting in free radical products

Question 16

What is the second stage of a free radical reaction called and how do you recognise one

Answer 16

Propagation, wear free radicals react with other molecules to create more free radicals. Free radicals reactants and products

Question 17

What is the final stage of a free radical reaction called and how do you recognise it

Answer 17

Termination, when two radicals react together resulting in non radical products

Question 18

How do halogen atoms affect the boiling point of a hydrocarbon

Answer 18

The larger the halogen atom (so the lower down the group) the higher the boiling point

Question 19

Name the 4 regions of the atmosphere, lowest to highest

Answer 19

Troposphere, stratosphere, mesosphere and thermosphere

Question 20

Why were CFC’s so popular?

Answer 20

They were very unreactive, low toxicity and low flammability

Question 21

What refrigerant did CFC’s replace and why?

Answer 21

Ammonia and because it was toxic and foul smelling

Question 22

What free radical breakdown ozone?

Answer 22

Chlorine

Question 23

In what part of the atmosphere do CFC’s breakdown?

Answer 23

Stratosphere

Question 24

What are the advantages and disadvantages to replacing CFC’s with hydrochlorofluorocarbons?

Answer 24

Advantage, HC bonds are broken down in the troposphere before it reaches the stratosphere
Disadvantage, it’s a green house gas and contributed to global warming

Question 25

What are the advantages and disadvantages to replacing CFC’s with alkanes?

Answer 25

Advantage, alkanes don’t contain chlorine

Disadvantage, flammable and a green house gas

Question 26

What cause CFC’s to breakdown in the stratosphere?

Answer 26

UV radiation

Question 27

Explain why heating up a molecule speeds up rate of reaction

Answer 27

More molecules have energy greater than the activation energy which is the energy molecules need to react when they collide

Question 28

Why does increasing concentration increase the rate of reaction

Answer 28

There are more collisions per unit time resulting in faster reaction

Question 29

Describe what it is meant by the term nucleophile

Answer 29

A species with a lone pair which forms a covalent bond with a positively charged carbon atom