Organic Chemistry p67-74 Flashcards

1
Q

What is the general formula for ethene?

A

CnH2n (for all alkenes)

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2
Q

What is the Empirical formula for ethene?

A

CH2

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3
Q

What is the molecular formula for ethene?

A

C2H4

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4
Q

What is the structural formula for ethene?

A

CH2CH2 (remember displayed)

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5
Q

What is homologous series?

A
  • group of compounds that can all be represented by the same general formula
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6
Q

Are alkanes a homologous series?

A

-yes
-only contain carbon and hydrogen atoms

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7
Q

What do molecules in a homologous series contain?

A

-contain the same functional group

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8
Q

What is a functional group?

A

-group of atoms that determine how a compound typically reacts
-this means compounds in homologous series typically react in similar ways

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9
Q

What are the four functional groups of homologous series?

A
  • Alcohols
    -Alkenes
    -Carboxylic Acid
    -Esters
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10
Q

What is the stem if the number of carbons is 1?

A

meth-

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11
Q

What is the stem if the number of carbons is 2?

A

eth-

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12
Q

What is the stem if the number of carbons is 3?

A

prop-

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13
Q

What is the stem if the number of carbons is 4?

A

but-

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14
Q

What is the stem if the number of carbons is 5?

A

pent-

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15
Q

What is the stem if the number of carbons is 6?

A

hex-

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16
Q

When are two molecules isomers of each other?

A
  • when they have the same molecular formula but the atoms are arranged differently
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17
Q

Why can you look for differently shaped carbon chains when spotting Isomers?

A

-carbons could be arranged differently
-e.g as a straight chain or branched (one of the carbons being bonded to more than two carbons) in different ways

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18
Q

Why will the physical properties of an isomer be different?

A
  • because of the change in shape of the molecule
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19
Q

Why can you have functional groups in different places when spotting an Isomer?

A
  • arrangement of carbon atoms could be the same
    -isomers could have the same functional group
    -but the functional group could be attached to a different carbon atom
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20
Q

Why can you have different functional groups when spotting an Isomer?

A
  • same atoms could be arranged in different functional groups
    -these isomers have very different physical and chemical properties
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21
Q

How are different compounds in crude oil separated?

A
  • by fractional distillation
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22
Q

What is crude oil?

A
  • a mixture of substances
    -most of which are hydrocarbons
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23
Q

What are hydrocarbons?

A
  • molecules which are made of only carbon and hydrogen only
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24
Q

What is the method for fractional distillation when crude oil is separated?

A
  • oil is heated until most of it has turned into gas
    -gases enter a fractionating column
    -in the column there is a temp gradient (when substances that make up the crude oil reach a part of the column where the temp is lower than their boiling point, they condense)
    -bubble caps in fractionating column stop separated liquids from running back down the column and remixing
    -you end up with he crude oil mixture separated into different fractions
    -each fraction contains a mixture of hydrocarbons with similar boiling points
  • and also saturated and unsaturated hydrocarbons
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25
Q

What do saturated hydrocarbons contain?

A
  • single bonds between carbon atoms
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26
Q

What do unsaturated hydrocarbons contain?

A
  • double or triple bonds between carbon atoms
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27
Q

What are refinery gases?

A
  • 3 carbons
  • used in domestic heating and cooking
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28
Q

What is Gasoline?

A
  • 8 carbons
  • used as a fuel in cars
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29
Q

What is Kerosene?

A
  • 15 carbons
  • used as a fuel in aircraft
30
Q

What is Diesel?

A
  • 20 carbons
  • used as a fuel in some cars and larger vehicles (trains)
31
Q

What is Fuel Oil?

A
  • 40 carbons
  • used as a fuel for large ships and also in some power stations
32
Q

What is Bitumen?

A
  • 70+ carbons
  • used to surface roads and roofs
33
Q

What do long hydrocarbons have?

A
  • high boiling points
  • viscous (thick and gloopy)
34
Q

What do shorter hydrocarbons have?

A
  • lower boiling points
  • much thinner and paler in colour
35
Q

What is the demand for hydrocarbons?

A
  • short chain hydrocarbons like octane (used in petrol) is much higher demand than long-chain hydrocarbons
36
Q

How do you meet the demand for hydrocarbons?

A
  • long chains of hydrocarbons are split into more useful short-chain molecules using cracking
37
Q

What is cracking?

A
  • form of thermal decomposition, which just means breaking molecules down into simple molecules by heating them
38
Q

What does cracking also produce?

A
  • produces alkenes
  • used to make polymers
39
Q

What are vaporised hydrocarbons passed over?

A
  • a powdered catalyst at about 600 degrees- 700 degrees
  • Silica or alumina are used as the catalyst
40
Q

What can you use for cracking?

A
  • vaporised alkane
  • a mixture of shorter chain alkanes and alkenes
  • catalyst
41
Q

What happens during the cracking experiment?

A
  • alkane is heated until it is vaporised
  • it then breaks down when it comes into contact with a catalyst
  • producing a mixture of short chain alkanes and alkenes
42
Q

What happens when you burn a fuel?

A
  • it releases energy in the form of heat
43
Q

What is burning also know as?

A
  • a combustion reaction
  • (substance being burned reacts with oxygen)
44
Q

Why do hydrocarbons make great fuels?

A
  • because the combustion reactions that can happen when you burn them in oxygen give out lots of energy
  • reactions are exothermic
45
Q

What happens when you burn hydrocarbons in plenty of oxygen?

A
  • products are carbon dioxide and water
  • this is called complete combustion
46
Q

What is the equation for complete combustion?

A

hydrocarbon + oxygen = carbon dioxide + water

47
Q

When do you get incomplete combustion?

A
  • when there is not enough oxygen around for complete combustion
48
Q

What do the products of complete combustion contain?

A
  • less oxygen then carbon dioxide
49
Q

What does incomplete combustion produce?

A
  • carbon monoxide
  • a toxic gas and carbon in the form of soot
50
Q

What can carbon monoxide combine with?

A
  • with red blood cells and stop your blood from doing its job of carrying oxygen around the body
  • lack of oxygen in the blood supply to the brain can lead to fainting, a coma or death
51
Q

What are a lot of the fractions obtained from crude oil burnt as?

A
  • fuels
52
Q

What happens when the fuels are burnt in the reaction with crude oil?

A
  • sulfur dioxide and nitrogen oxides may be produced
  • sulfur dioxide comes with sulfur impurities in the hydrocarbon fuels
53
Q

When are nitrogen oxides created?

A
  • when the temp is high enough for the nitrogen and the oxygen in the air to react
54
Q

What do nitrogen oxides include?

A
  • nitrogen monoxide
  • nitrogen dioxide
55
Q

What happens when sulfur dioxide and nitrogen oxides mix with water vapour in clouds?

A
  • they form dilute sulfuric acid and nitric acid
  • rain that falls from these clouds is called acid rain
56
Q

What does acid rain cause?

A
  • lakes to become acidic, many plants and animals can die
57
Q

What are alkanes?

A
  • hydrocarbons
  • chains of carbon atoms surrounded by hydrogen atoms
58
Q

What do alkanes make up?

A
  • majority of hydrocarbons in crude oil
  • tend to combust completely in a good supply of oxygen
59
Q

What is an example of alkanes burning in a combustion reactions? (propane)

A

propane + oxygen = carbon dioxide + water

60
Q

What do chlorine and bromine react with alkanes in the presence of?

A
  • ultra violet light
61
Q

What is a substitutional reaction?

A
  • hydrogen atom from the alkane is substituted with chlorine or bromine
  • this is how bromine and methane react together to form bromomethane
62
Q

What are alkenes?

A
  • hydrocarbons which have a double bond between two of the carbon atoms in their chain
63
Q

Why are alkenes unsaturated molecules?

A
  • they cant make more bonds
  • double bond can open up, allowing the two carbon atoms to bond with other atoms
64
Q

What are the first three alkenes?

A
  • ethene
  • propene
  • butene
65
Q

What do Halogens react with alkenes to form?

A
  • Haloalkenes
66
Q

Why is Dibromoethane an additional reaction?

A
  • the C=C double bond is split and a halogen atom is added to each of the carbons
67
Q

What is the reaction between bromine and alkenes often used as a test for?

A
  • carbon-carbon double bonds
68
Q

What happens when you shake an alkene with orange bromine water?

A
  • the solution becomes colourless
    -this is because the bromine molecules which are orange are reacting with the alkene to make dibromoalkane which is colourless
69
Q

Why dont alkanes react with bromine water?

A
  • they dont have a double bond
70
Q

What would happen if you add an alkane to bromine water?

A
  • the solution will stay orange