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Chemistry Year 1 > 6.2 > Flashcards

6.2 Flashcards

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1
Q

what happens in fractional distillation

A

Crude oil is heated in a furnace Which time is it into vapour which passes into column

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2
Q

what is inside the fractioning column

A

There is a temperature gradient.
It’s hotter at the bottom and cooler at the top.

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3
Q

what happens once crude oil vapour enters the fraction column

A

The vapour then reached the faction, which is slightly higher than its BP, causing it to condense.

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4
Q

what is the extra step to fractional distillation

A

Some hydrocarbons reach the top without condensing. These then undergo further fractional distillation separately.

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5
Q

what is cracking

A

the process of converting long chain hydrocarbons into smaller ones and also forming an alkene

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6
Q

what are the steps of cracking

A

The hydrocarbons are passed in the heavier fractions through a heated catalyst (usually zeolite).

This causes the hydrocarbons to break into smaller alkane + alkene and sometimes hydrogen is also produced.

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7
Q

What is reforming

A

turning straight hydrocarbon chains into cyclic

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8
Q

how does reforming happen

A

Hydrocarbons are heated with a catalyst usually platinum.

This makes it more cyclic and have more branches.

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9
Q

what is complete combustion

A

Reaction where a molecule is reacted with oxygen (when there is a plentiful supply) to form CO2 + H2O and all atoms are fully oxidised.

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10
Q

what is incomplete combustion

A

Reaction with insufficient oxygen to produce carbon monoxide as well as water and carbon in solid form. Some atoms are not fully oxidised.

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11
Q

what is carbon monoxide

A

A colourless + odourless gas that prevents transportation of O2 in the body.

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11
Q

how are oxides of sulphur formed

A

A colour + odourless gas that prevents transportation of O2 in the body.

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12
Q

how do these oxides contribute to acid rain

A

Both these gases dissolve in the water rand form sulphuric acid which contributes to acid rain.

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13
Q

what damage do these cause

A

damage to aquatic live, damage to crops + forest.

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14
Q

how are oxides of nitrogen formed

A

Few alkane molecules contain nitrogen.

When nitrogen undergoes combustion, it forms oxides of nitrogen (NOx)

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15
Q

how is nitrogen monoxide formed

A

N+O2 = 2NO (nitrogen monoxide

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16
Q

how is nitrogen dioxide formed

A

2NO + O2 = 2NO2 (Nitrogen dioxide)

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17
Q

how is nitric acid formed

A

2NO2 + H2O = HNO2 +HNO3 (nitrogen acid +nitric acid)

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18
Q

how do catalytic converters work

A

Fitted in a cars exhaust system to reduce pollution

Made of small quantities of precious metals which are spread thinly over a honeycomb mesh (to increase the S.A for reaction).

It oxides the pollutants.

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19
Q

equations in catalytic converters

A

2CO +O2 = 2CO2

2NO + 2CO = N2 + 2CO2

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20
Q

what are biofuels

A

Biofuels are obtained from living matters which died recently.

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21
Q

what are the 2 types of biofuels

A

Biodiesel
Bio-alcohal

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22
Q

what is biodiesel

A

Biodiesel is a fuel made from vegetable oil obtained from plant.

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23
Q

what is bio-alcohal

A

Fuels made from plant matter often using enzymes or bacteria

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24
Q

land use, yield, manufacture/transport, carbon neutrality of biofuels

A

Land use = a lot of land is needed meaning it compromised land for food.

Yield = low but it is gradually increasing.

Manufacture/ transport = NO exploration or drilling cost. Substantial cost in growing, processing and transport.

Carbon neutrality=is low

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25
Q

Land use, yield, manufacturing/transport, carbon neutrality of natural gas

A

Natural gas

Land use = no land needed as it comes from underground.

Yield=very high

Manufacturing/transport=Exploration and drilling cost is high. Low processing cost. Transport cost is low by pipeline.

Carbon neutrality-not carbon neutral

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26
Q

what is a substitution reaction & formula equation

A

A reaction where an atom or group is replaced by another atom or group
CH4 + Cl = CH3Cl + HCL

27
Q

what is a mechanism

A

a sequence of steps in an overall reaction. Each step shows what happens to the electron involved in the bond breaking or bond formation

28
Q

\What is a radical

A

a species that contains an unpaired electron

29
Q

what is homolytic fission

A

is the breaking of a covalent bond where each of the bonding electrons leaves with one species forming a radical

30
Q

what happens in initiation
& formula example

A

involved the formation of radicals due to a bond breaking caused by U.V

Cl2 = Cl. + Cl.

31
Q

what happens in propogation & example

A

reaction between one free radical and a normal molecule to produce another free radical and one molecule.

Cl. + CH4 = CH3. + HCL then
CH3. + Cl2 = CH3Cl + Cl.

32
Q

what happens in termination & examples

A

2 radicay6huls react to form a molecule

Cl. + Cl. = Cl2
Cl. + CH3. = CH3Cl
CH3. + CH3. = C2H6

33
Q

what are the bonds in a double bond

A

Sigma
pi

34
Q

what is a sigma bond

A

a covalent bond that’s formed when 2 s orbitals overlap horizontally/ axially ( end - on)

35
Q

what happens in a sigma bond

A

a strong electrostatic force of attraction is formed between nuclei and shared electrons due to high electron density between nuclei

36
Q

what is pi bond

A

covalent bond is formed by parrallel overlap of 2 p orbital lobes sideways.

37
Q

why is sigma bond stronger

A

sigma bonds are stronger as there is a higher electrons density which is spread out over a smaller area ( only between nuclei ) the electrostatic attraction is higher and therefore have higher bond enthalpy

38
Q

why are double bonds more reactive than single

A

pi bonds are more reactive as they are spread out over a large area. Due to the high electron density it attracts many electrophiles causing it to react with many compounds

39
Q

what is an addition reaction

A

reactin in which 2 molecules become 1 by combining

40
Q

what is hydrogenation

A

an addition reaction in which hydrogen is added to an alkene to form an alkane .

41
Q

what is used in hydrogenation

A

a nickel catalyst

42
Q

what is an example of hydrogenation

A

manufacturing of margarine.
- veg oils are unsaturated and reacted with hydrogen to turn it into margarine.

43
Q

why do they do this

A

margarine is a healthier option

44
Q

what is halogenation

A

reaction where a halogen is added

45
Q

what is hydration

A

reaction where H2O is added

46
Q

how does this reaction happen

A

Takes place by heating alkene with steam and passing the mixture over a catalyst of phosphuric acid.It forms an alcohal

47
Q

what is an electrophile

A

a species that is attracted to a region of high energy electron density

48
Q

Electrophilic addition

A

reaction where 2 molecules form 1 and the attacking molecule is an electrophile

49
Q

hetrolytic fission

A

breaking of a covalent bond so both bonding electrons are taken by one atom

50
Q

what is polymerisation

A

A process where small molecules called monomers join together into larger molecules called polymers that consist of repeating molecules

51
Q

what is addition polymerisation

A

All the atoms in the monomers are used to form polymer

52
Q

what is condensation reaction

A

Monomers join up with the expulsion of small molecules while not every origional atoms are present within the polymer

53
Q

What is a repeating unit

A

The set of atoms that are joined together in large numbers to produce the polymer structure

54
Q

why are polymers used

A
  • manufactured on a large scale with variety
  • Light
  • Cheap
  • Unreactive so they can be used to make many things
55
Q

what does biodegradable mean

A

can be broken down by microbes

56
Q

are polymers biodegradable or non-biodegradable

A

non-biodegradable

57
Q

how does Reduce usage of polymers help

A

Reducing polymer use unecessarily by dicouraging free plastic bags + using bags for life.

58
Q

how does recycling help

A

The polymers are turned into other materials and

59
Q

what are the 2 stages of recycling

A
  1. sorting polymers so it can be processed together effectively and appropiately
  2. Process it by chopping waste into small pieces + washing it and turning it into new material by; melting, mouldering, fibre production
60
Q

how does chemical feedstock help

A

breaking polymers into gasses to produce a feedstock that can be used in other chemical reactions

61
Q

how does incineration help

A

Takes polymers and converts into heat energy to generate electricity

62
Q

by is incineration bad

A

some polymers contain toxic metals ( which are used to pigment polymers ) which when burnt form toxic gasses.

63
Q

how does producing biodegradable polymers help

A

using polymers that are biodegradable

64
Q

how is this also bad

A

they are made from plant matherial which requires huge land space to grow + when they are broken down they release hydrogen + carbon atoms that can’t be used

Chemistry Year 1 (11 decks)

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