topic 7 - organic chemistry Flashcards

1
Q

hydrocarbon

A

compound formed with only hydrogen and carbon atoms

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2
Q

formula for alkanes

A

CnH2n+2

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3
Q

properties alkanes

A
  • saturated
  • shorter the chain the less viscous (more running)
  • shorter the chain the lower the boiling point
  • shorter the chain the more flammable
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4
Q

first 4 alkanes

A
  1. methane
  2. ethane
  3. propane
    4 . butane
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5
Q

complete combustion of any hydrocarbon

A

hydrocarbon + oxygen –> carbon dioxide + water
- releases huge amounts of energy - used as fuels
- both carbon and hydrogen from the hydrocarbon are oxidised

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6
Q

crude oil

A
  • fossil fuel
  • formed from remains of plants and animals that died billions of years ago particularly plankton
  • contains lots of different hydrocarbons with different properties
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7
Q

fractional distillation’s temp gradient

A
  • hotter at the bottom and cooler at the top
  • longer chain hydrocarbons have higher boiling points so condense to liquids at the bottom
  • shorter chain hydrocarbons have lower boiling poinst and so condense at the top later on
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8
Q

order of things that make it to the top of fractional distillation

A

TOP:
1. petrol
2. kerosene
3. diesel oil
4. heavy fuel oil
BOTTOM:

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9
Q

uses of oil

A
  • fuel for transport
  • polymers
  • solvents
  • lubricants
  • detergents
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10
Q

catalytic cracking VS steam cracking

A

thermal decomposition reaction
CATALYTIC: heat hydrocarbon to gas and pass over hot powdered aluminion oxide catalyst
STEAM: heat hydrocarbon to gas and mix with steam at very high tempertaures

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11
Q

whats an alkene

A
  • double bond
  • unsaturated
  • reactive bc double bond can open and react
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12
Q

first 4 alkenes

A
  1. ethene
  2. propene
  3. butene
  4. pentene
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13
Q

alkene formula

A

CnH2n

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14
Q

alkenes in incomplete combustion

A

alkene + oxygen —> carbon + carbon monoxide + carbon dioxide + water
- smokey yellow flame and less energy released

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15
Q

alkenes functional group

A

C=C

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16
Q

addition reaction of alkene and HYRDOGEN 1

A
  • hydrogen opens up the double bond to form a saturated alkane
  • needs a catalyst
  • called hydrogeneration
  • propene + catalyst —> propane
17
Q

addition reaction of alkene and steam/water 2

A
  • react with steam and water is added across the double bond forming alcohol
  • high temps to vaporise water
  • catalyst
  • eg - ethene + steam + catalyst = ethanol
  • to seperate - cool ethanol and ethen will stay as gas
    then to seperate the water and ethanol use fractional distillation
18
Q

addition reaction of alkene and HALOGENS 3

A
  • same as wiht hydrogen but no catalyst
  • bromine/chlorine/iodine
  • bromie and ethene react to make dibromoethane
  • organe to collourless
19
Q

bromine water test for alkenes

A
  • when bromine water added to alkene it will react and go colourless due to alkenes saturation