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Chemistry Year 12 > Assessment > Flashcards

Assessment Flashcards

(67 cards)

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1
Q

What are some different ways of extracting hydrocarbons?

A
  • Crude oil can be extracted from the ground using a drill
  • Hydraulic fracturing involves the extraction of natural gas from shale rock by using pressurised fracking fluid.
  • Mining can be used to access oil sands
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2
Q

What are the four main environmental implications of obtaining hydrocarbons?

A
  • dangerous crude oil extraction
  • climate change
  • oil spills
  • incomplete combustion
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3
Q

Why is the extraction of crude oil dangerous?

A

Extracting crude oil from underground reservoirs allow for empty cavities to form underground which may cause the overlying geography to collapse.

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4
Q

Why are oil spills dangerous?

A

They introduce dangerous chemicals into the environment and are extremely difficult to clean up.

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5
Q

What is an example of a oil spill?

A

The oil spill which occurred in 2010, on the Gulf of Mexico:
- 205.5 million gallons of oil was spilled
- 225 000 tons of methane was spilled
- only 25% was recovered
Death toll:
- 11 humans
- 6165 sea turtles
- 25 900 marine animals
- 82 000 birds

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6
Q

Why is incomplete combustion of hydrocarbons dangerous?

A

Incomplete combustion produces carbon monoxide, which is fatal once inhaled.

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7
Q

How do hydrocarbons contribute to climate change?

A

Methane which is unburned affects climate change more than completely combusted methane, as it traps more heat.
When fossil fuels are burned they released greenhouse gases which contributes to global warming.

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8
Q

How much has Earth’s temperature increased by?

A

0.06C per decade since 1850, with 2024 being 1.18C above the 20th century average.

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9
Q

What are some of the positive impacts hydrocarbons have had economically?

A
  • Significant energy output
  • Transportation flourished
  • development of plastics
  • development of advanced drugs
  • country exports (Saudi Arabia made $236 billion in 2022)
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10
Q

What are some of the negative economical impacts of hydrocarbons?

A
  • Increased price and scarcity of petroleum
  • Extra care needed to protect biodiversity
  • Leaking toxic hydrocarbons which may results in the death of aquatic organisms.
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11
Q

What are some of the positive sociocultural implications of using hydrocarbons

A
  • efficient and cheap heating and energy production
  • Suburban electricity for increased working hours
  • Satisfied demands
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12
Q

What are some negative implications of using hydrocarbons?

A
  • Workers drilling hydrocarbons can be exposed to rocks covered in poisonous hydrocarbon lubricants
  • Damaged aquatic ecosystems can led to increased seafood prices
  • Toxic hydrocarbons can leak into potable water. need for thorough research and funding for treatment
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13
Q

What are the two types of fuels made from organic substances?

A

fossil fuels and biofuels

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14
Q

What are some characteristics of fossil fuels?

A
  • They’re non-renewable
  • Made from fossilised animal and plant remains
  • Consists of coal, natural gas and oil
  • The combustion of fossil fuels provides large amounts of energy
  • Releases a lot of carbon dioxide
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15
Q

What are some characteristics of biofuels?

A
  • Renewable
  • Made with plant materials
  • bioethanol and biodiesel
  • Less of an effect on the environment due to the plants used to make the fuel using the CO2 the fuels release during photosynthesis.
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16
Q

What is the chemical composition of coal, petrol and natural gas?

A

Coal: carbon
Petrol: primarily alkane chains
Natural gas: primarily methane

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17
Q

What is the chemical composition of ethanol and biodiesel?

A

Ethanol: C2H5Oh
Biodiesel: an ester of different chain lengths

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18
Q

What is the enthalpy of combustion of natural gas, coal, and petrol?

A

Natural gas: 53.6
Coal: 9.8-27.9
Petrol: 48

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19
Q

What is the enthalpy of combustion of bioethanol and biodiesel?

A

Bioethanol: 29.6
Biodiesel: 37.2

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20
Q

What are the benefits of fossil fuels?

A
  • Produces lots of energy
  • Cost effective
  • Can be used in transportation
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21
Q

What are some limitations of fossil fuels?

A
  • Non-renewable
  • Significant health and environmental issues
  • Unsustainable
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22
Q

What are the benefits of biofuels?

A
  • Renewable
  • More sustainable
  • Lowered costs
  • Environmentally friendly
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23
Q

What are some limitations of biofuels?

A
  • Land use concerns
  • Potential for deforestation
  • Less energy efficient
  • May require significant energy during production
  • Reliance on agriculture
  • Can contain impurities
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24
Q

What is the Haber Process?

A

The synthesis of ammonia: N2 + 3H2 –> 2NH3

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25
What is the process of synthesising ammonia?
1) Nitrogen and hydrogen are extracted and pumped through pipes 2) The pressure is increased to 200 atmosphere - this shifts equilib to the right 3) The temperature is increased to 450C and ran through a tank containing an iron catalyst 4) Reaction is cooled so ammonia can liquify and be removed as it is made 5) liquid NH3 is collected and excess H and N are recycled
26
What is a soap?
A soap is a substance made from natural fats or oils with a strong alkali, made for the use of washing and cleaning.
27
What are addition polymers?
Polymers made through the combination of monomers
28
What is polyethylene?
PE is the product of multiple ethylene monomers joining together. During the reaction the double bonds in the ethylene break, allowing the monomers to join together.
29
What are the two main types of PE?
- Low-density polyethylene - High-density polyethylene
30
What is LDPE?
- Produced using temperatures of 3000C - Produced using pressures of 1000-3000 times atmosphere - Uses an initiator - Creates branched polymer chains which prevents monomers forming close together
31
What are the properties of LDPE?
- Less dense - Flexible - Lower melting point - Amorphous structure
32
What is HDPE?
- Produced at much lower temperatures of 60C - Produced at a pressure 2-5 times atmospheric - Uses trimethylaluminum, a Ziegler-Natta catalyst - Produces linear, unbranched chains
33
What are some properties of HDPE?
- More dense - rigid stucture - Higher melting point - Less flexible - More crystalline
34
What are some applications of PE?
- Packaging equipment: crates, drums, films, trays, bottles, plastic bags - Agricultural mulch - Insulation for wires and cables
35
What is PVC?
Polyvinylchloride - a polymer in which one hydrogen has been replaced with a chlorine atoms
36
What effect does chlorine have on the molecule?
Due to the chlorine being extremely electronegative, the monomers are more closely compacted allowing for dipole-dipole bonds to occur between chains
37
What are some properties of PVC?
- Extremely hard and rigid - Greater melting point - Poor conductor - Water insoluble - chemically resistant
38
What are plasticiers?
Little molecules which can be added to polymers to hold the chains further apart, weakening the bonds. This makes the polymer more flexible
39
What are some applications of PVC?
- Pipes and machinery - Chemical storage and insulators - Tank fittings
40
What is PS?
Polystyrene - a polymer made of styrene monomers, which are known as ethenylbenzene. A phenyl group replaces one hydrogen in each monomer
41
Why are PS rigid?
Due to the bulkiness of the C6H5 group.
42
What are some properties of PS?
- Rigid - Amorphous - Transparents - Brittle
43
What are the two types of PS?
- Crystal polystyrene - Expanded polystyrene
44
What are some characteristics of crystal PS
- Rigid - Transparent - Can be moulded into a specific shape when heated and cooled - Chemically resistant to redox reactions - Traps gas
45
What are some applications of crystal PS?
- Car batteries - Hard plastic furniture - Tool handles - Heat-pressed food packaging - Food containers - Eating utensils
46
What are some characteristics of expanded PS?
- Can be moulded into specific shapes when heated and cooled - Reduced heat and sound wave transmission - Light - High compressibility - Brittle
47
What are some applications of expanded PS?
- Protective packaging material - Insulation - Protective casing
48
What is PTFE?
Polytetrafluroethylene - a polymer in which all the hydrogens have been replaced with flourine.
49
What are some properties of PTFE?
- High crystalline structure - High melting point - Resistance to chemicals - Chemical inertness - Translucent to opaque - Non-stick - Significantly low friction
50
What are some applications of PTFE?
- low friction machine components - chemical pipelines - non-stick cookware - electrical insulation in computers and aircrafts - medicinal applications
51
What is a surfactant?
A soap of detergent - lowers the surface tension of water by interrupting the hydrogen bonds
52
What is an emulsifier?
A compound that can cause immiscible liquids to mix.
53
What is a micelle?
A soap surrounded grease or dirt particle which remains suspended in water, when previously it had no affinity to the water substrate
54
What is a soap?
A substance made from natural fats or oils with a strong alkali.
55
What is the equations for making a soap?
triglycerides + sodium hydroxide --> sodium carboxylic acids (soap) + glycerol
56
What is the structure of a soap?
A long hydrocarbon chains which is hydrophobic and a hydrophilic head containing a carboxylate ion and its ionicly bonded cation (Na, K)
57
Why do the tails bond with the greases?
The tail is non-polar, as it the greases. They have the ability to create dispersion forces.
58
Why do the heads bond with water?
Both the head and the water are polar, which allows for ion-dipole forces to occur.
59
What are detergents?
Detergents are very similar to soaps, however they are synthetic and can exhibit different hydrophilic heads.
60
What are the three types of detergents?
- Anion detergent (SO3) - Cationic detergent (N + 3 branched CH3) - Non-ionic detergent: no ionic bonds and uncharged
61
What are ionic detergents used for?
- Laundry - Household cleaning - Dishwashing
62
What are cationic detergents used for?
- Hair conditioners - Sanitisers - Fabric softeners - Disinfectants
63
What are non-ionic detergents used for?
- Dishwashing - Glass cleaner
64
How do you made a powder detergent?
1) raw ingredients are added to a slurry mixer 2) Mixture is heated to 85 and stirred until a homogeneous slurry forms 3) The slurry is deaerated, separated into droplets, and sprayed into a column of air at 425. 4) The base powder is then mixed in a fluidiser with other ingredients.
65
How are liquid detergents made?
1) a soap premix is created which is neutralised with caustic soda or KOH 2) The ingredients are mixed at a high temp 3) The mixture is cooled and milled, and enzymes are added.
66
How do soaps and detergents work?
As they are surfactants, the surface tension of the water is lowered, allowing for it to be spread. The hydrophilic head will create ion-dipole bonds with the water whilst the non-polar, hydrophobic tales will form dispersion bonds with the grease. As the water is agitated water molecules pull on the soap molecules. Micelles will form as the soap molecules encircle the dirt, and can be rinsed away with water.
67
How do the action of soaps and detergents differ in hard water?
Soaps can form precipitates call soap scum. Detergents do not.

Chemistry Year 12 (4 decks)

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