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Chemistry > topic 8 > Flashcards

topic 8 Flashcards

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1
Q

how is crude oil formed ?

A

when remains of plants and animals are buried and under high pressure and temperature eventually form this finite resource

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2
Q

what is crude oil ?

A

a complex mixture of hydrocarbons

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3
Q

what can crude oil be separated into and based on what ?

A

fractions based on the chain length of hydrocarbons (similar number of carbon and hydrogen atoms)

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4
Q

what is used to separate crude oil into different fractions ?

A

fractional distillation

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5
Q

longer hydrocarbons drain out at the bottom of the columns as

A

they have the greatest boiling/melting point

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6
Q

shorter hydrocarbons drain out at the top since they have

A

lowest boiling/melting point

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7
Q

summarise what happens in fractional distillation.

A

the oil is heated and turns into gas. these gases enter a fractionating column and are drained off based on boiling point

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8
Q

what is a homologous series?

A

series of molecules or compounds with the same general formula, functional group and similar chemical properties

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9
Q

fractions of crude oil from top to bottom

A 
gases 
petrol 
kerosene 
diesel oil 
fuel oil 
bitumen
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10
Q

what are gases used for?

A

cooking

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11
Q

what is petrol used for ?

A

car fuel

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12
Q

what is kerosene used for?

A

plane fuel

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13
Q

what is diesel oil used for ?

A

car fuel

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14
Q

what is fuel oil used for ?

A

fuel for large ships and power stations

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15
Q

what is bitumen used for?

A

roads and roofs

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16
Q

why do physical properties of elements from a homologous series vary?

A

as bigger molecules have a grater boiling point etc.

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17
Q

what determines properties of an element/compound

A

it’s size / chain length / intermolecular forces

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18
Q

why do bigger molecules have a grater boiling/melting point ?

A

since the intermolecular forces of attraction are much stronger since there is more forces to break

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19
Q

why are shorter molecules easier to ignite

A

since they have a lower boiling point

also since they’re usually gases they mix with oxygen which is flammable.

20
Q

why do shorter molecules have a low viscosity

A

as they have less forces of attraction between molecules making them easier to flow

21
Q

why do longer molecules have a high viscosity

A

there is more stronger forces of attraction between molecules making it harder to flow

22
Q

how can we make hydrocarbons release energy

A

by burning them in oxygen and since they’re exothermic they release a lot of energy

23
Q

equation for complete combustion?

A

hydrocarbon + oxygen = carbon dioxide + water

24
Q

when does incomplete combustion occur ?

A

when there isn’t sufficient oxygen

25
Q

what is produced during incomplete combustion?

A

carbon monoxide and carbon(as soot)

26
Q

what can carbon monoxide cause ?

A

it can combine with red blood cells and stop the job of carrying oxygen

the lack of oxygen leads to fainting coma or even death

27
Q

what can carbon(soot) cause?

A

they deposit themselves on buildings making them dirty and reducing air quality

also can cause or worsen respiratory problems

28
Q

how is sulfur dioxide released and what does it cause?

A

sulfur dioxide is released from burning fossil fuels, it can mix with clouds and fall as acid rain. it can make lakes acidic and causing organisms to die as a result

29
Q

how is nitrogen oxide created and how is it harmful ?

A

created from a reaction between nitrogen and oxygen in the air - usually caused by combustion reactions

it contributes to acid rain and can cause a photochemical smog

30
Q

advantages of using hydrogen fuel ?

A

very clean only waste is water

renewable

can be obtained from a renewable source

31
Q

disadvantages of using hydrogen fuel ?

A

requires a special expensive safe.

to make hydrogen gas energy from a source is required

hydrogen is hard to store and not widely available

32
Q

what is cracking ?

A

a process of thermal decomposition where one substance breaks down into two new one with heat

33
Q

what does cracking require ?

A

lot of heat to break strong covalent bonds

catalyst is required

34
Q

why is cracking used ?

A

to suit the demand for different molecules

35
Q

what does cracking turn and what into ?

A

turns long saturated (alkanes) into smaller unsaturated (alkenes)

36
Q

summarise the process of cracking…

A
  1. vaporised hydrocarbons are passed over a powdered catalyst at high pressure and temperature
    aluminium oxide is the catalyst used
37
Q

what catalyst is used in cracking?

A

aluminium oxide

38
Q

what happened during the phase 1 of the creation of atmosphere ?

A

as volcanoes kept erupting after earth cooled a lot of carbon dioxide methane ammonia and steam was released. early atmosphere consisted of water vapour and co2 but th vapour condensed to form oceans

39
Q

what happened at phase 2 of the creation of atmosphere?

A

Co2 dissolved into oceans. Nitrogen was put into the atmosphere from ammonia reacting with oxygen. Green plants evolved and photosynthesised to increase oxygen and decrease carbon dioxide. Most co2 got caught in rocks (fossil fuels)

40
Q

what happens during phase 3 of the creation of atmosphere ?

A

organisms died or evolved to adapt to oxygen. oxygen caused the creation of an ozone layer that blocked sun rays

no co2 at this point

41
Q

how do you test for oxygen?

A

place a glowing splint in oxygen and if it relights oxygen is present

42
Q

what are the greenhouse gases and what do they do ?

A

they reflect and absorb heat radiation

carbon dioxide water vapour methane

43
Q

what kind of radiation does the sun give out?

A

electromagnetic radiation

44
Q

what happens during the greenhouse effect ?

A

earth radiates some of the heat radiation it absorbs

some IR radiation is absorbed by greenhouse gases

some IR is reflected back to earth by greenhouse gases

some IR is reflected back into space

45
Q

how is methane produced ?

A

in digestive processes of livestock

Chemistry (5 decks)

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