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Chemistry > C9/10: Hydrocarbons > Flashcards

C9/10: Hydrocarbons Flashcards

1
Q

alkanes general formula?

A

CnH2n+2

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2
Q

names of alkanes and molecular formula?

A

METHANE - CH4
ETHANE - C2H6
PROPANE - C3H8
BUTANE - C4H10

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3
Q

hydrocarbons?

A

compound that only conatisn hydrogen and carbon atoms.

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4
Q

franction distillation of crude oil?

A
  1. crude oil enters bttom of colum as HOT VAPOUR
  2. Vapour rises/vapours with high BP condense lower down in column
  3. vapours with lower BP condense high up column
  4. different fraction condense at different levels according to BP (get colder up the column)
    5.fractions containing BIGGER HYDROCARBONS collected at bottom/SMALER collected at top
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5
Q

properties of alkanes?

A

BP increases as molcule gets bigger (intermolecular forces are larger due to more electrons/greater SA contact with them, so more energy is needed to break them)

VISCOCITY - as molecules get bigger, so do IF
- MORE VISCOUS , BETTER LUBRICANTS

FLAMMABILITY - INCREASED SIZE, LESS FLAMMABLE

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6
Q

combustion of alkanes eg

A

methane + oxygen —> carbon dioxide + water

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7
Q

ALKANES?

A

saturated hydrocarbons containing single bonds only

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8
Q

ALKENES?

A

unsaturated hydrocarbons containing double bonds

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9
Q

what is cracking?

A
  • converts long chain of alkane molecules into samller chain molecules that are more useful
  • ALKENES/HYDROGEN are produced using this process
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10
Q

process of CATALYTIC CRACKING?

A
  1. heat hydrocarbon to 470-550 to vaporise them
  2. vapours pass over hot powdered ctatalyst of ALUMINIUM OXIDE
  3. this breaks covalent bonds, causing THERMAL DECOMPOSITION
  4. molecules are broken up RANDOMLY to produces smaller alkanes/alkenes
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11
Q

process of steam cracking?

A
  1. vaporised hydrocarbons are mixed with steam/heated at high temps which induces cracking
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12
Q

alkenes general formula?

A

CnH2n

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13
Q

what happens when alkenes are added to bromine water?

A
  • addition reaction
  • ALKENES turn bromine water COLOURLESS, because the double bond breaks and each bromine is bonded with each carbon , so no Bromine atoms are free, so loses its colour
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14
Q

Names of alkenes and molecular formula?

A

ETHENE : C2H4
PROPENE: C3H6
BUTENE: C4H8
PENTENE : C5H10

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15
Q

INCOMPLETE COMBUSTION OF ALKENES?

word equn

A

Butene + Oxygen —> Carbon MONOXIDE + water

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16
Q

REACTION OF HYDROGEN WITH ALKENES ?

Give word equn/conditions/explain

A

pentene + hydrogen —> pentANE
- becuase of C=C bond , moleucles dnt contain max no. hydrogens
- addition of H2 atoms across double bond forms an ALKANE (SATURATED HYDROCRABON)

CONDITIONS: 150 degrees using NICKEL catalyst

17
Q

Reaction of steam and ALKENES ?

word equn/conditions for reaction

A

ethene + steam —-> ETHANOL
- alcohol produced becuase O - H bond added AND C= C bond becomes single
conditions:
- 330 degrees
- 60-70 atm
- concentarted phosphoric acid catalyst

18
Q

Reaction of halogens with alkenes?

word equn

A

ethene + chlorine —> dichloroethane
C=C turns to single bond

19
Q

alcohols general formula?

A

CnH2n+1OH

20
Q

Alcohol name and molecular formular ?

A

METHANOL : CH3OH
ETHANOL: C3CH2OH
PROPANOL : C3CH2CH2OH
BUTANOL : C3CH2CH2CH2OH

21
Q

Fermnetation to produce alcohol?

conditions/word equn

A

CONDITIONS -fermented between 25 degrees +
- no oxygen
Glucose + enzymes —-> ethanol + Co2

22
Q

combustion of alcohol

word equn

A

ethanol + oxygen —> carbon dioxide + water

23
Q

reaction of alcohol with oxidising agent?

word equn

A

ethanol + oxidising agent —> ethanoic acid + water
FORMS CARBOXYLIC ACID+ WATER

24
Q

Reaction of alcohol with sodium?

A

sodium + methanol —> sodium methoxide + hydrogen
- PRODUCE HYDROGEN GAS/METAL SALT

25
Q

carboxylic acids general formula?

A

CnH2n+1COOH

26
Q

Reaction of carboxylic acids with carbonates ?

word equn

A
  • a metal salt, carbon dioxide and water are produce
    ethanoic acid + potassium carbonate —-> potassium ethanoate + water+ carbon dioxide
27
Q

Reaction of carboxylic acids with magnesium?

word equn

A
  • salt and hydrogen is produced
    ethanoic acid + magensium —> hydrogen + magensium ethanoate
28
Q

how are esters made ?

word equn/reactants needed

A

combine alcohol with carboxylic acid
- use acid catalyst (sulfuric acid)
ethanoic acid + ethanol —> ethyl ethanoate + water

29
Q

propetries of esters and functional group?

A

R-COO-R
- sweet smell
- volatile

30
Q

are carboxylic acids weak or strong acids/why?

A

weak - dissolve in water but only PARTIALLY IONISE
- reaction are every slow

31
Q

Uses of ethanol

A

Solvents
Antiseptic
Fuel

32
Q

carboxylic acids names and molecular formula?

A

methanoic acid : HCOOH
ethanoic acid : CH3COOH
propanoic acid : CH3CH2COOH
butanoic acid : CH3CH2CH2COOH

33
Q

uses of petrohemical substances

A

solvents
lubricants
polymers

Chemistry (15 decks)

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