7 Organic chemistry Flashcards

1
Q

formuala for alkanes

A

CnH2n+2

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2
Q

what does saturated hydrocarbon mean

A

contains no carbon-to-carbon double bonds, only single bonds

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3
Q

properties of short hydrocarbons

A
  • the shorter the carbon chain the less vicous it is
  • the shorter carbon chain the more volatile they are - lower boiling point
  • the shorter the more flamable

opposite for longer hydrocarbons

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4
Q

complete combustion

A
  • happens when burning a staurated hydrocarbon eg. alkane and alcohol
  • saturated hydrocarbon + oxygen —> carbon dioxide + water
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5
Q

what is crude oil

A
  • fossil fuel
  • made from plants and animals that died million years ago - over this period high tmep and pressure turned reamians to crude oiil
  • drilled up from the rocks where it’s found
  • non-renweable fuels
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6
Q

why do we use fractional distilation

A
  • to seperate the different compunds in crude oil
  • each hydrocarbon length has different uses
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7
Q

how do fractional distillation columns work

A
  • oil is heated until most of it turns into a gas
  • gas enters the fractionating column
  • in the column there is a temperature gradient- hot at bottom cooler as you go up
  • the longer hydrocarbons with higher boiling points condense back into liquids and drain out the column near the bottom
  • shorter hydrocarbons have lower boiling points so condense much later on near the top of the column where its cooler
  • end up with crude oil misture seperated out into different fractions
  • each fraction contains a mixture of hydrocarbons that contain similiar number of carbon atoms so have similiar boiling points
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8
Q

hydrocarbon uses and their lengths

A
  • very short - petroluem gas
  • short - petrol
  • somewhat long - kerosene
  • long - diesiel oil
  • very long - heavy fuel oil
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9
Q

what is a homolgous series

A
  • a family of hydrocarbons with similar chemical properties who share the same general formula
  • eg, alkanes, alkenes, alcohols, carboxylic acids
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10
Q

what is cracking

A
  • splitting up long-chain hydrocarbons into smaller ones
  • thermal decompostion reaction - breaking molecules down by heating them
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11
Q

why do we do cracking

A
  • long-chain hydrocarbons aren’t very useful
  • however short-chain hydrocarbons are useful since they’re flamable so make good fuels and are highly in demand
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12
Q

products of cracking

A

long-chain hydrocarbon —> short-chain hydrocarbon + alkene

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13
Q

how do you crack a hydrocarbon

A
  • heat long chain hydrocarbons to vaporsie them
  • the vapour is passed over a hot powdered aluminium oxide catalyst
  • long-chain molecules split apart on the surface of catalyst - catalytic cracking
  • can also crack them by after vaporising mixing with steam and then heating to a very high temp - steam cracking
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14
Q

what is an alkene

A
  • hydrocarbon with a double C=C bond
  • CnH2n
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15
Q

what is an unsaturated hydrocarbon

A

contains carbon-to-carbon double bonds

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16
Q

incomplete combustion

A
  • happens when burning alkenes
    alkene + oxygen —> carbon + carbon monixide + cabron dioixde + water
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17
Q

how do alkenes react

A
  • via addition reactions
  • the C=C opens up to leve a single bond and a new atom is added to each cabrons
18
Q

what happens when you react a hydrogen and alkene

A
  • hydrogenation
  • hydrogen opens up the double bond and forms an equivelant, saturated alkane
  • eg:
    R H…………………….. H H
    C=C + H2 —> R - C - C - H
    H H …………………… H H

r - hydrocarbon

19
Q

what happens when steam is added to alkenes

A
  • forms alcohol
  • ethene is mixed with steam forming ethanol
    industrial making:
  • after reaction takes place, mixture passed from reactor to condenser
  • ethanol and water have higher boling points than ethene so both condense whilst unreacted gas ethene is recycled back to the reactor
  • alcohol is then purified by fractional distilation
20
Q

what happens when you add a halogen to an alkene

A
  • halogens break C=C bond
  • each C=C bond becomes bonded to a halogen atom
  • eg.
    H H…………………….. H Br
    C=C + Br2 —> H - C - C - H
    H H …………………… Br H
21
Q

describe what happens when you add bromine to alkenes

A
  • when orange bromine water is added to alkene the bromine will add accross the double bond making a colourless dibromo-compound
  • so bromine water decolourised
22
Q

whats a functional group

A

goup of atoms that determines how that molecule typically reacts
- alkane - C=C
- alcohol - OH
- Carboxylic acids - COOH
- Ester -COO-

23
Q

what are polymers

A
  • long molecuels formed when lots of small molecules called monomers join
  • usually carbon based
  • monomers often alkenes
24
Q

how to draw polymers

A
  • n infornt of bracket with double bond inside - write type of monomer
  • in bracket single bond, bonds drawn extending out of brackets with n after the bracket - write poly(type of monomer)
25
Q

how to write an alcohol formula

A

with OH to show functional group
eg. not CH4O instead CH3OH

26
Q

porperties of first 4 alcohols

A
  • flammable, undergo complete combustion in air
  • all soluble in water
  • have a neutral pH
  • react with sodium - one product is hydrogen
  • can be oxidised to produce carboxylic acid
  • different alcohols form diff carboxylic acids
27
Q

uses of alcohols

A
  • used as solvents, can dissolve most things including things water can and can’t
  • used as fuels
  • alcoholic drinks
28
Q

how else can ethanol be made

A
  • through fermentation
  • used in alcoholic drinks
    sugar —> ethanol + carbon dioxide
  • happens at 37 degrees, slightly acidic and anaerobic conditions
29
Q

carboxylic acid properties

A
  • names end in “-anoic acid”
  • react with carbonates to produce salts, water and CO2
  • salts formed end with -anoate
  • dissolve in water, ionise releasing H+ ions forming acidic solution, don’t completely ionise so form weak acid solution, have higher pH
30
Q

how are esters formed

A
  • formed from alochols and carboxylic acids
  • alcohol + carboxylic acid —> ester + water
31
Q

what are esters

A
  • organic compounds , functional group -COO-
  • Esters have fruity smells and can be used as solvents and perfumes
32
Q

what is condensation polmeristaion

A
  • involves monomers with different fucntional groups
  • react making polymer chains between them
  • for each new bond a smaller molecule is created eg. water
33
Q

addition vs condenstaion polymeristaion no. of types of monomers

A
  • Add. - only one monomer containg C=C
  • Con. - 2 monomer types containing 2 of the same functional groups OR one monomer type with 2 different functional groups
34
Q

addition vs condenstaion polymeristaion no. of products

A
  • Add. - one product formes
  • Con. - 2 products form - polymer and small molecule eg. water
35
Q

addition vs condenstaion polymerisation functional groups involved

A
  • Add. - C=C bond in monomer
  • Con. - 2 reactive groups on each monomer
36
Q

naturally occuring polymers

A
  • amino acids
  • protiens, polymers of amino acids
  • DNA - made from nucelotide polymers
  • simple sugars from polymers
37
Q

amino acid functional group

A
  • basic amino group NH2
  • acidic carboxyl group COOH
38
Q

how are proteins formed

A
  • amino acids form polymers - polypeptides through condenstaion poylmeristaion
  • amino group of an amino acids reacts with acidic groups of others to form a polymer chain, for every new bond water is lost
  • one or more long-chains of polypeptides are protiens
  • polypeptides and proteins that can contain different amino acids in their polymer chains
  • order of amino acids is what gives protiens their properties and shapes
39
Q

what is DNA made from

A
  • made of 2 polymer chains of monomers called nucleotides - contain a small molecule, a base - ACGT
  • bases on different polymer chains pair up with each other and form cross links keeps the 2 strands of nucelotide strands together
  • order of bases acts as a code for an organism’s genes
40
Q

how do simple sugars form polymers

A
  • sugars are small molecules containing carbon, oxygen and hydrogen
  • can react together through polymeristaion reactions to form larger carbohydrate polymers eg. starch - store of energy and cellulose - use in plant cell walls