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Chemistry > alkanes+haloalkanes(p2) > Flashcards

alkanes+haloalkanes(p2) Flashcards

1
Q

what is fractional distillation?

A

a method of separating crude oil fractions using their boiling points

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2
Q

describe how crude oil separates in the fractioning column

A
  1. vaporised at 350 degrees
  2. passes into fractioning column using temperature gradient
  3. as they pass up they condense +cool
    highest temprature at the bottom, lowest at the top
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3
Q

what occurs at the top and bottom of the fractioning column?

A

lowest BP dont condense so are drawn out as gases at the top. larger hydrocarbons dont vaporise so stay at bottom as residue

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4
Q

what are the two types of cracking?

A

catalytic+steam(thermal)

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5
Q

what are the conditions of catalytic cracking?

A

zeolite catalyst
500 degrees

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6
Q

what does catalytic cracking produce?

A

aromatic hydrocarbons+alkanes

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7
Q

what are the conditions of steam cracking?

A

up to 1000 degrees, 70 atmospheres

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8
Q

what does steam cracking produce?

A

alkenes

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9
Q

what is a free radical?

A

a particle with an unpaired electron

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10
Q

give the mechanism of a free radical substitution between a chlorine free radical and methane to make a haloalkane

A
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11
Q

give the complete combustion equation of propane

A

C3H8+502=4H20+3CO2

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12
Q

give the incomplete combustion equation for propane

A

C3H8+31/2=3CO=4H20

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13
Q

What is ozone?

A

a chemical sunscreen, absorbs UV radiation from the sun, which can cayse sunburn/skin cancer

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14
Q

give the free radical mechanism of ozone formation

A
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15
Q

what is a problem chloroflourocarbons(CFCs) in our atmosphere?

A

destroys ozone as chlorine free radicals can form

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16
Q

give the free radical mechanism for the destruction of ozone

17
Q

why is nitrogen monoxide dangerous and how is it formed?

A

it is produced when high pressure and high temperature in a car engine cause nitrogen and oxygen in the air to react with each other= toxic,poisonous

18
Q

give the reaction of nitrogen monoxide reacting further to form nitrogen dioxide

A

N2+O2=2NO
2NO+O2=2NO2

19
Q

why are nitrogen oxides especially dangerous with hydrocarbons?

A

as all fuel isnt burnt, when these two react it forms gorund level ozone which can irritate eyes,aggravate respiratory problems

20
Q

what is the purpose of a catalytic converter?

A

remove nitrogen oxides, unburnt hydrocarbons, carbon monoxide from exhausts

21
Q

when burnt why are fossil fuels particulary dangerous?

A

they contain sulfur so when burnt it forms sulfur dioxide and if this in the atmopsher it can dissolve and is converted to sulfuric acid which can lead to acid rain, this is the same with NO2

22
Q

how can sulfur dioxide be removed from flue gases?

A

powdered calcium carbonate mixed with water=used as they neutralise sulfur dioxide. it is then sprayed in SO2 gas

23
Q

give the reaction between sulfur dioxide and calcium carbonate

A

CaO+SO2=CaSO3

24
Q

how do you make a haloalkane?

A

alkane+halogen in a free radical substitution

25
Q

give the equation for the incomplete combustion of butane forming soot

A

C4H10=2.5O2–> 4C+5H2O

26
Q

how does CO2 contribute to global warming?

A

CO2 absorbs infra red radiation from sun and emits some of it back to earth (greenhouse effect) in turn increasing global temperature

27
Q

what is the BP trend going down haloalkanes?

A

BP increase as stregnth of van der waals increase as size of molecule increases. require more energy to overcome

28
Q

what are the reactivity of haloalkanes?

A

stronger the bond enthalpy, the less reactive. so going down the group the more reactive

29
Q

how do chlorofluorocarbons break down ozone?

A

C-Cl bonds are weaker then C-F bonds therefore can break in presence of UV radiation creating chlorine radicals which can attack ozone

30
Q

give the mechanism for the reaction of a haloalkane with aqueous potassium hydroxide

31
Q

what are the conditions for the reaction of aqueous potassium hydroxide and a haloalkane to form an alcohol?

A
  • warm aqueous hydroxide
  • under reflux
32
Q

give the mechanism for the reaction between potassium cyanide and a haloalkane

33
Q

what are the conditions for the reaction of potassium cyanide and a haloalkane

A
  • warm ethanolic cyanide
    -reflux
34
Q

give the mechanism between ammonia and a haloalkane

35
Q

what are the conditions for ammonia reacting with a haloalkane to form an amine?

A
  • excess ethanolic ammonia
  • high pressure as ammonia will evaporate
36
Q

give two equations to show why both cyanide and ammonia have to be ethanolic when reacting with haloalkane

37
Q

give the elimination reaction between ethanolic potassium hydroxide and a haloalkane. what does it form?

38
Q

what are the conditions for the elimination reaction between hydroxide and a haloalkane?

A
  • ethanolic hydroxide
  • reflux

Chemistry (25 decks)

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