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chemistry paper 2 > organic chemistry- topic 7 > Flashcards

organic chemistry- topic 7 Flashcards

(52 cards)

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1
Q

what is a hydrocarbon?

A

a compound of hydrogen and carbon

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2
Q

what is crude oil?

A

a mixture of compounds (mainly hydrocarbons)

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3
Q

how is crude oil formed?

A

-formed from the remains of ancient biomass (mainly plankton) buried in mud
-formed under conditions of high temperature and pressure and found in rocks
-finite resource

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4
Q

what are alkanes?

A

saturated hydrocarbons with the general formula (CnH2n+2)

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5
Q

what are the alkanes?

A

acronym: monkeys methane
eat ethane
peanut propane
butter butane

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6
Q

what is a homologous series?

A

series of compounds with the same general formula, same functional groups and similar chemical properties

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7
Q

describe the combustion of hydrocarbons

A

-exothermic reaction occurring when hydrocarbons are reacted with oxygen
-complete combustion produces carbon dioxide + water (carbon and hydrogen atoms are completely oxidised)
-incomplete combustion produces carbon + carbon monoxide + water

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8
Q

what is the equation for complete combustion?

A

alkane (fuel) + oxygen –> carbon dioxide + water

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9
Q

what is the equation for incomplete combustion?

A

fuel –> carbon monoxide + carbon + water

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10
Q

describe the physical properties of alkanes

A

-first few in series are gases, then change to liquids then solids
-boiling points + viscosity increase as molecules get bigger
-volatility and flammability decrease as molecules get bigger
-poor reactivity

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11
Q

what are the properties of long-chain hydrocarbons?
flammability=
boiling point=
viscosity=

A

low flammability
high boiling point
high viscosity

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12
Q

what are the properties of short-chain hydrocarbons?
flammability=
boiling point=
viscosity=

A

high flammability
low boiling point
low viscosity

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13
Q

are hydrocarbons used as fuels? why?

A

yes, because when they react with oxygen they react with a lot of energy

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14
Q

what is the process of fractional distillation?

A
  1. crude oil is heated and vaporised
  2. vapour rises up the fractionating column
  3. the column is hotter at the bottom and cooler at the top
  4. hydrocarbons cool as they go up the column and condense at diff points as they have diff boiling points
  5. large molecules = high boiling points, collected at bottom
  6. small molecules = low boiling points, collected at top
  7. hydrocarbon fraction is collected
  8. crack the hydrocarbons using high temperatures and either steam or a catalyst
  9. you are left with smaller, more useful molecules
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15
Q

what fuels do we depend on for our modern lifestyle?

A

petrol, diesel oil, kerosene, heavy fuel oil and liquefied petroleum gases, are produced from crude oil

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16
Q

what useful materials do our modern life depend on ?

A

solvents, lubricants,
polymers, detergents are produced by the petrochemical industry

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17
Q

what is cracking?

A

Hydrocarbons can be broken down (cracked) to produce smaller, more useful molecules.
long chain alkane –> shorter alkane + alkene

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18
Q

what are 2 methods of cracking?

A

catalytic cracking and steam cracking

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19
Q

what type of reaction is cracking?

A

thermal decomposition

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20
Q

what is the process of catalytic cracking?

A

-vaporise the hydrocarbons
-pass over a hot catalyst

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21
Q

what is the process of steam cracking?

Study These Flashcards
A

-vaporise the hydrocarbons
-mix with steam at very high temperatures

22
Q

what are some conditions for cracking?

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A

-contain a feedstock
- catalyst
- high temperatures

23
Q

how are the products of cracking used?

Study These Flashcards
A

the products are alkanes and alkenes- used as polymers and starting materials for synthesis

24
Q

what is an alkene?

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A

unsaturated hydrocarbon. contains a C=C double bond.
general formula is: CnH2n

25
what is the test for alkenes?
when mixed with bromine water it should change from orange to colourless
26
why is there a demand for short-chain hydrocarbons?
some of the products of cracking are useful as fuels because they are highly flammable
27
what are the alkenes?
ethene (eat) propene (peanut) butene (butter) pentene
28
describe the combustion of alkenes
they burn with smoky flames due to incomplete combustion
29
describe addition reactions of alkenes
- addition atoms across the carbon-carbon double bond becomes a single carbon-carbon bond (a) with hydrogen- hydrogenation; requires a higher temperature and a nickel catalyst (b) with steam- hydration; requires high temperature, pressure and concentrated phosphoric acid (H3PO4) as a catalyst (c) with bromine, chlorine, iodine, addition of halogens (same as hydrogenation but doesn't require catalyst)
30
what is an alcohol?
an organic compound that contains the -OH functional group
31
what is the general formula for alcohols?
CnH2n+1OH
32
state characteristics of methanol, ethanol, propanol and butanol
-dissolve in water to form a neutral solution -react with sodium to form hydrogen (+product called alkoxide e.g ethanol + sodium --> sodium ethoxide + hydrogen) -burn in oxygen -react with carboxylic acids in presence of acid catalyst to form esters
33
what do alcohols react with to form carboxylic acids?
oxidising agent
34
what are some uses of alcohols?
-fuels (especially short-chain alcohols as they combust easily, forming carbon dioxide and water) -solvents (can dissolve things water can't e.g fats +oils) -drinks
35
how are alcohols formed?
in fermentation of sugar (warmed mixture of sugar and yeast) glucose--> ethanol + carbon dioxide
36
state the conditions required for fermentation of glucose + equation of the reaction
-30 degrees -aqueous solution of glucose -absence of air -yeast added C6H1206--> 2CH3CH2OH + 2CO2
37
what are carboxylic acids?
organic compounds that contain a -COOH functional group
38
what are the first 4 carboxylic acids?
methanol acid, ethnic acid, propanoic acid, butanoic acid
39
state characteristics of carboxylic acids
-dissolve in water to form an acidic solution (contains H+ ions) -react with metal carbonates to form carbon dioxide -react with alcohols with an acid catalyst to produce esters -react with metals to give off hydrogen gas
40
what type of acid is a carboxylic acid?
a weak acid
41
explain why carboxylic acids are weak acids
they are partially dissociated, thus the pH of a carboxylic acid in solution is not as low as a solution of a strong acid of the same concentration
42
what is an ester and how is it formed?
-an organic compound containing a -COO- functional group, formed from carboxylic acid and alcohol in the presence of a sulphuric acid catalyst -they have a fruity smell
43
what is the equation for forming an ester + key example?
alcohol + carboxylic acid --> ester + water -e.g. ethanol + ethnic acid --> ester + water
44
what is a polymer? how do molecules containing a C=C bond form polymers?
- a polymer is a long chain molecule which is made by lots of smaller molecules (monomers) joining together. - C=C bonds open up and many smaller molecules (monomers) join together to form a chain (polymer) - it is called an addition polymerisation reaction
45
how does the repeating unit relate to the monomer in addition polymerisation?
The repeat unit has the same atoms as the monomer because no other molecule is formed in the reaction
46
give the examples of addition polymers and their uses
-poly(ethene) -- plastic bags -poly(tetrafluoroethene (PTFE)--teflon surfaces, for uses in non-stick kitchenware -poly(chloroethene) (PVC) -- water pipes
47
what is condensation polymerisation?
- involves monomers with 2 functional groups - many molecules join together; the polymer is formed but also a small molecule is released e.g. water, hydrochloric acid - polyesters e.g. terylene - polyamides e.g. nylon
48
what monomers and products are used and made during condensation polymerisation?
monomers - diols, carboxylic acids or diamonds products - polymers and water
49
what is an amino acid?
an organic compound (natural polymer) that ​have​ ​two​ ​different​ ​functional​ ​groups​ ​in​ ​a​ ​molecule​ ​(an​ ​amine​ ​group​ (-NH2) ​and​ ​a carboxylic​ ​acid​ ​group)
50
how do amino acids make proteins? what are polypeptides?
by numerous condensation polymerisation reactions. proteins are polymers made of amino acids (monomers) -polypeptides are also made by ​ ​condensation​ ​polymerisation​ of amino acids, but are shorter than proteins
51
what is dna and its role?
DNA (deoxyribonucleic acid a large molecule essential for life- it encodes genetic instructions for the development and functioning of living organisms and viruses
52
what is the structure of dna?
- made up of two monomer chains that are held together in a double helix - each polymer chain can be made from 4 different monomers- nucleotides

chemistry paper 2 (2 decks)

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