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Chemistry > C8 Fuels and Earth science > Flashcards

C8 Fuels and Earth science Flashcards

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1
Q

What are hydrocarbons?

A

compounds containing only carbon and hydrogen

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2
Q

As a carbon chain increases in length, what happens to the state of matter and why?

A
  • carbon chain increases
  • gases -> liquids -> solids
  • due to stronger forced between molecules
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3
Q

What is volatility?

A

how easy it us for a substance to change states of matter

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4
Q

As a carbon chain increases in length, what happens to the volatility and why?

A
  • carbon chain increases
  • volatality decreases
  • stronger forces between molecules

-harder to break therefore change states

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5
Q

As a carbon chain increases in length, what happens to the boiling point and why?

A
  • carbon chain increases
  • boiling point increases
  • stronger forced between molecules
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6
Q

What is viscosity?

A

-measure of how fluid(runny) a substance is

low viscosity: runny, pours easily
high viscosity: not runny, won’t poor easily

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7
Q

As a carbon chain increases in length, what happens to the viscosity?

A
  • carbon chain increases

- viscosity increases

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8
Q

As a carbon chain increases in length, what happens to the flammability(ease to ignite) and why?

A
  • carbon chain increases
  • flammability decreases
  • stronger forces between molecules
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9
Q

What is a homologus series?

A
  • has the same general formula
  • differ by CH2 unit
  • similar chemical properties
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10
Q

What does saturated/unsaturated mean?

A

saturated - single bonds only

unsaturated - contains at least one double/triple bond

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11
Q

Are alkanes saturated or unsaturated?

A
  • saturated

- no double bonds

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12
Q

Are alkenes saturated or unsaturated?

A
  • unsaturated

- contains a double bond

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13
Q

What is the general formula for alkanes?

A

CnH2n+2

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14
Q

What is the general formula for alkenes?

A

CnH2n

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15
Q

What are the first four alkanes?

A

methane CH4
ethane C2H6
propane C3H8
butane C4H10

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16
Q

What are the first three alkenes?

A

ethene C2H4
propene C3H6
butene C4H8

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17
Q

What is a functional group?

A

group if atoms responsible for the properties in an organic compound

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18
Q

What is the functional group in an alkene?

A

C=C bond

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19
Q

What colour changes occur when bromine is added to alkane and why?

A

colourless + brown/orange -> brown/orange

alkanes do not react to bromine
-because they are saturated

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20
Q

What colour changes occur when bromine is added to alkene and why?

A

colourless + brown/orange -> colourless

alkenes react with bromine
-because they are unsaturated

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21
Q

What is crude oil?

A
  • mixture of hydrocarbons

- mixture meaning two or more substances combined withiut being chemically bonded together

22
Q

How do we seperate hydrocarbons in crude oil?

A

fractional distillation

23
Q

Why does fractional distillation work for the seperation of hydrocarbons in crude oil?

A
  • different hydrocarbons have different boiling points

- lowest boiling point evaporates first and condenses at cooler temperature

24
Q

What are the properties of hydrocarbon molecules which condense at the coolest and hottest temperatures (top+bottom) of fractional distillation?

A

coolest temp/ top:

  • small molecules
  • low boiling point
  • high volatility
  • high flammability
  • low viscosity

hottest temp/ bottom:

  • large molecules
  • high boing point
  • low volatility
  • low flammability
  • high viscosity
25
Q

What 3 things are produced/released in complete combustion of hydrocarbon fuels?

A
  • carbon dioxide
  • water
  • energy released
26
Q

What is a fuel?

A
  • any substance burned in oxygen
  • releases energy
  • exothermic reaction
27
Q

What is the order of prioritisation when balancing equations?

A
  • metals
  • non metals
  • hydrogen
  • oxygen
28
Q

What does the incomplete combustion of hydrocarbons produce and why?

A
  • carbon
  • carbon monoxide
  • carbon dioxide
  • water

-not enough oxygen available for complete combustion to occur

29
Q

Why is carbon monoxide a toxic gas?

A

-colourless + odourless
so cant be seen + smelt

  • binds to haemoglobin in red blood cells
  • reduced volume of oxygen carried by blood cells to cells in body
30
Q

What is soot and why is it hazardous?

A

-solid carbon particles

-block boiker jets meaning less energy is released
-makes everything dirty
-can cause health problems if inhaled
–lung damage
–breathing difficulties

31
Q

How do hydrocarbon fuels produce sulfur dioxide?

A
  • hydrocarbon fuels burned in oxygen
  • impurities -> sulfur
  • react with oxygen instead
  • sulfur + oxygen -> sulfur dioxide
32
Q

What happens when sulfur dioxide dissolves in rain water?

A

-sulfurous acid formed

–acid rain

33
Q

What environmental problems are associated with acid rain?

A

-waterways become more acidic
–increase in death of plants + animals

-kills trees

  • reacts with calcium carbonage in limestone and marble
  • weathering occurs
  • damaging builing/ statues
34
Q

How are nitrogen oxides formed in the burning of hydrocarbon fuels and why is this bad?

A
  • at high temperatures
  • in combustion engines
  • oxygen reacts with nitrogen
  • nitrogen oxides formed
  • contributes to acid rain
  • can cause photochemical smog
35
Q

What are the advantages of using hydrogen fuel cells rather than petrol as fuel in cars?

A
  • hydrogen can be obtained from water produced
  • no pollutants
  • only produce water as waste
  • plenty of water/raw materials
36
Q

What are the disadvantages of using hydrogen fuel cells rather than petrol as fuel in cars?

A
  • electricity needed for electrolysis
  • gas leaks are common if the fuel system is damaged
  • hydrogen is hard to store as it is very flammable
  • hydrogen is expensive to produce
  • hydrogen is hard to find on the market to buy
  • hydrogen requires vehicles to have bigger, stronger, heavier fuel tanks
  • the elctricity needed comes from burning fossil fuels which produces CO2 so pollutants are released in the process
37
Q

What is cracking?

A
  • breaking down/ thermal decomposition
  • larger, molecules (alkanes)
  • into smaller, useful ones (some alkene)
38
Q

Why is cracking necessary?

A

-shorter chain molecules are more useful
-more demand for shorter chain molecules
-reduced amount of long chain molecules
-produces alkenes
–used to make polymers

39
Q

What gases formed the Earth’s early atmosphere produced by volcanoes?

A

gases produced by volcanoes

  • CO2
  • H2O
  • NH3
40
Q

What was the Earth’s early atmosphere thought to contain?

A
  • little/no oxygen
  • large amounts of CO2
  • water vapour
  • small amount of other gases
41
Q

How were oceans formed?

A
  • over a billion years the earth started to cool
  • lower temp means water vapour could condense into rain
  • over a few hundred million years of rainfall oceans formed
42
Q

How did the formation of oceans cause CO2 levels to decrease?

A
  • plants evolved in the oceans
  • photosynthesis in the plants removed CO2 from the atmosphere
  • causing the % to decrease
43
Q

How did the formation of oceans cause CO2 levels to decrease? (CO2 is soluble)

A
  • CO2 begun to dissolve in the rain and oceans
  • marine organisms began to evolve on Earth
  • some adapted to use CO3 dissolved in the water
  • created exoskeletons/shells (eg crabs)
  • marine organisms then died
  • sink to the bottom of the sea and build up and form sediment
  • sediment compacted overtime to form carbonate rocks eg limestone/chalk
44
Q

What is the test for oxygen?

A
  • glowing splint

- reignites

45
Q

How did levels of oxygen gradually increase on Earth?

A
  • growth of primitive planta
  • photosynthesis
  • releases oxygen so gradual increase in %
46
Q

Describe the green house effect and name the gasses involved

A

CO2, CH4, H2O

  • short wave EM radiation from the sun is absorbed by the Earth’s surface
  • short wave radiation is re-emitted as long wave IR radiation
  • some IR radiation reflected back into space
  • greenhouse gases absorb the reflected IR radiation and re-radiate it in all directions including back towards the Earth

since the radiation is IR, warming if the surface of the Earth is a result

47
Q

What does evidence of atmospheric CO2 concentration and temperature change over time show us?

A

CO2 causes global warming

  • as CO2 conc increase global temperatured increase
  • CO2 is causing global warming

CO2 doesn’t cause global warming

  • as CO2 conc increases global temperatures increase but fluctuates
  • so this does not prove evidence CO2 increase is causing the Earth’s temperature to rise
  • as CO2 conc increases global temperatures increase
  • but there are other factors that may cause the increase in global temperatures
48
Q

What is the Earth’s current atmosphere?

A
  • nitrogen (mainly)
  • oxygen
  • water

-argon and other gases

49
Q

How does farming contribute to climate change?

A
  • livestock and rice release methane
  • methane is a greenhouse gas
  • increasing population means increasing demand for more farms
  • more farms means more methane
50
Q

How does burning fossil fuels contribute to climate change?

A
  • more CO2
  • more IR radiation absorbed and re-emitted
  • more global warming
51
Q

How can we mitigate (lessen) the effects of climate change?

A

-personally
–reducing carbon footprints
–choosing options thats do not involve fossil fuels eg less driving less heating

-governmental
–investigating in renewable energy resources

-new technology
–eg the Thames barrier is designed ti prevent flooding

Chemistry (10 decks)

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