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C8 Fuels and Earth science Flashcards

(51 cards)

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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?

Study These Flashcards
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?

Study These Flashcards
A

fractional distillation

23
Q

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

Study These Flashcards
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?

Study These Flashcards
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
What 3 things are produced/released in complete combustion of hydrocarbon fuels?
- carbon dioxide - water - energy released
26
What is a fuel?
- any substance burned in oxygen - releases energy - exothermic reaction
27
What is the order of prioritisation when balancing equations?
- metals - non metals - hydrogen - oxygen
28
What does the incomplete combustion of hydrocarbons produce and why?
- carbon - carbon monoxide - carbon dioxide - water -not enough oxygen available for complete combustion to occur
29
Why is carbon monoxide a toxic gas?
-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
What is soot and why is it hazardous?
-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
How do hydrocarbon fuels produce sulfur dioxide?
- hydrocarbon fuels burned in oxygen - impurities -> sulfur - react with oxygen instead - sulfur + oxygen -> sulfur dioxide
32
What happens when sulfur dioxide dissolves in rain water?
-sulfurous acid formed | –acid rain
33
What environmental problems are associated with acid rain?
-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
How are nitrogen oxides formed in the burning of hydrocarbon fuels and why is this bad?
- at high temperatures - in combustion engines - oxygen reacts with nitrogen - nitrogen oxides formed - contributes to acid rain - can cause photochemical smog
35
What are the advantages of using hydrogen fuel cells rather than petrol as fuel in cars?
- hydrogen can be obtained from water produced - no pollutants - only produce water as waste - plenty of water/raw materials
36
What are the disadvantages of using hydrogen fuel cells rather than petrol as fuel in cars?
- 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
What is cracking?
- breaking down/ thermal decomposition - larger, molecules (alkanes) - into smaller, useful ones (some alkene)
38
Why is cracking necessary?
-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
What gases formed the Earth's early atmosphere produced by volcanoes?
gases produced by volcanoes - CO2 - H2O - NH3
40
What was the Earth's early atmosphere thought to contain?
- little/no oxygen - large amounts of CO2 - water vapour - small amount of other gases
41
How were oceans formed?
- 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
How did the formation of oceans cause CO2 levels to decrease?
- plants evolved in the oceans - photosynthesis in the plants removed CO2 from the atmosphere - causing the % to decrease
43
How did the formation of oceans cause CO2 levels to decrease? (CO2 is soluble)
- 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
What is the test for oxygen?
- glowing splint | - reignites
45
How did levels of oxygen gradually increase on Earth?
- growth of primitive planta - photosynthesis - releases oxygen so gradual increase in %
46
Describe the green house effect and name the gasses involved
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
What does evidence of atmospheric CO2 concentration and temperature change over time show us?
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
What is the Earth's current atmosphere?
- nitrogen (mainly) - oxygen - water -argon and other gases
49
How does farming contribute to climate change?
- livestock and rice release methane - methane is a greenhouse gas - increasing population means increasing demand for more farms - more farms means more methane
50
How does burning fossil fuels contribute to climate change?
- more CO2 - more IR radiation absorbed and re-emitted - more global warming
51
How can we mitigate (lessen) the effects of climate change?
-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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