T7 organic chemistry Flashcards

1
Q

what is crude oil

A

mixture of compounds; a fossil fuel consisting of the remains of ancient biomass

finite resource - can’t be replaced as it is used up

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2
Q

what is a hydrocarbon

A

compound made up exclusively of hydrogen and carbon atoms

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3
Q

what are alkanes

A

saturated hydrocarbons of a general formula

CnH2n+2 (where n is the number of carbon atoms in the molecule).

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4
Q

what is a homologous series

A

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

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5
Q

describe the combustion of hydrocarbons

A
  • exothermic reaction occurring when hydrocarbons are reacted with oxygen
  • complete combustion produces carbon dioxide and water (carbon and hydrogen atoms are completely oxidised)
  • incomplete combustion produces carbon or carbon monoxide and water
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6
Q

describe the physical properties of alkanes

A
  • first few in series are gases, then change to liquids, then to solids
  • in general, boiling points and viscosity increase as molecules get bigger
  • volatility and flammability decrease as molecules get bigger
  • poor reactivity
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7
Q

explain how fractional distillation of crude oil takes place

A
  • crude oil is heated and vaporised
  • vapor rises up the fractionating column
  • column is hotter at bottom
  • hydrocarbons cool as they go up the column and condense at different heights as they have different boiling points
  • large molecules, high boiling points, collected at bottom
  • this gives fractions which can be used in various ways
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8
Q

what is cracking

A

when large hydrocarbons are thermally broken down into smaller and useful molecules

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9
Q

what type of reaction is cracking

A

thermal decomposition

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10
Q

what are the conditions for cracking

A

reactant heated to vapor, passed over a hot catalyst (catalytic cracking) or heated to vapor, mixed with steam and heated to high temperatures (steam cracking)

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11
Q

how are the products of cracking used

A

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

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12
Q

what is an alkene

A

unsaturated hydrocarbon, contain C=C bond

general formula CnH2n

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13
Q

what is the test for alkenes

A

add bromine water

colour change occurs from orange to colourless

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14
Q

describe the combustion of alkenes

A

burn with smoky flames due to incomplete combustion

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15
Q

describe addition reactions of alkenes

A

additions atoms across the carbon-carbon double bond so that the 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 Br2/Cl2/I2 - addition of halogens

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16
Q

what is an alcohol

A

organic compound that contains and -OH functional group

17
Q

state characteristics of methanol, ethanol, propanol and butanol

A
  • dissolve in water to form a neutral solution
  • react with sodium to form hydrogen
  • burn in oxygen
  • react with carboxylic acids in presence of acid catalyst to form esters
18
Q

oxidation of the alcohols leads to…

A

carboxylic acids

19
Q

what are some uses of alcohols

A

fuels
solvents
drinks

20
Q

state the conditions required for fermentation of glucose and state the equation of the reaction

A

30C, aqueous solution of the glucose, absence of air, yeast added

C6H12O6 > 2CH3CH2OH + 2CO2

21
Q

what are carboxylic acids

A

organic compounds that contain a COOH functional group

22
Q

state characteristics of carboxylic acids

A
  • 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
23
Q

what type of acid is carboxylic acid

A

weak aid

24
Q

explain why carboxylic acids are weak acids

A

partially dissociated in water, thus the pH of a carboxylic acid in solution is not as low as a solution of a strong acid of the same concentration

25
Q

what is an ester and how is it formed

A

organic compound containing a -COO- functional group, formed from carboxylic acid and alcohol in the presence of a sulfuric acid catalyst

have a fruity smell

26
Q

what is a polymer

how do molecules containing C=C bond form polymers

A

long chain molecule which is made by lots of smaller molecules joining together

C=C bonds open up and many smaller molecules (monomers) join together to form a chain (a polymer)

called an addition polymerisation reaction

27
Q

give 3 examples of addition polymers and their uses

A

polyethene - plastic bags

(poly) tetrafluoroethene (PTFE) - teflon surfaces, for use in non-stick kitchenware
(poly) chloroethene (polyvinylchloride, PVC) - water pipes

28
Q

what is a repeating unit of a polymer

A

it is a smallest structure which, upon numerous translations, yields the structure of the polymer

in addition polymers: to draw it, take a monomer, change C=C to C-C and show additional single bonds extending away from these carbons

29
Q

what is a condensation polymer

A

polymer made in condensation polymerisations

in this reaction, many molecules join together, polymer is formed but also a small molecule is released

polyesters eg terylene
polyamides eg nylon

30
Q

what is an amide bond

A

similar to the ester bond with O replaced by N
(C=O)-NH2
contains C=O group like an ester

31
Q

what is an amino acid

A

organic compound that contains both a carboxylic acid functionality (COOH) and an amine functional group (-NH2)

32
Q

how do amino acids make proteins

what are polypeptides

A

numerous condensation polymerisation reactions; proteins are polymers made of amino acids

made by condensation polymerisation of amino acids but are shorter than proteins
proteins can be seen as a product of many polypeptide chains bonded together

33
Q

what are carbohydrates

A

organic molecules made of C, H and O
biologically relevant eg starch and cellulose

both of these are polymers made of glucose (other carbohydrate) monomers

their structures differ in the way the glucose molecules are joined together

34
Q

what is DNA

describe its role and structure

A

material that makes up chromosomes - cell structures that store genetic information

made up of 2 polymer chains that are held together in a double helix

each polymer chain can be made from 4 different monomers - nucleotides

deoxyribonucleic acid