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Edexcel IGCSE Chemistry > Section 4: Organic Chemistry > Flashcards

Section 4: Organic Chemistry Flashcards

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1
Q

What is the general formula of an alkane and alkene

A

Alkane = CnH2n+2, Alkene = CnH2n

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2
Q

What does it mean if a molecule is saturated or unsaturated? Which group do alkanes and alkenes belong to?

A

Saturated - only single bonds, alkanes.

Unsaturated - at least one double bond, alkenes.

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3
Q

Describe the difference between complete and incomplete combustion

A

Complete - happens in excess oxygen - produces carbon dioxide and water.

Incomplete - happens in limited oxygen - produces carbon monoxide and water

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4
Q

Give the equation for the addition reaction of ethene and bromine.

Explain how it is an addition reaction.

What observations would be made?

A

C2H4 + Br2 -> C2H4Br2.

It is an addition reaction because the double bond break and hydrogen is added to the molecule(2 reactants to 1 product).

Colour change orange to colourless

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5
Q

What is the difference between but-1-ene and but-2-ene?

A

The double bond is in a different position

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6
Q

Describe and explain the effect of increasing chain length on boiling point

A

As chain length increases so does the boiling point as the intermolecular forces between molecules become stronger

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7
Q

Name the process by which ethene is produced from crude oil

A

Cracking

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8
Q

Give the chemical equation for ethene reacting with steam and the conditions of this reaction

A

C2H4(g) + H2O(g) –> C2H5OH(g)

300oC, 60-70 atm pressure and phosphoric acid catalyst

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9
Q

Give the chemical equation for the fermentation of glucose to produce ethanol. What are the conditions for the reaction

A

C6H12O6 (Enzymes in yeast) —> 2C2H5OH + 2CO2

30oC, yeast enzyme, no oxygen

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10
Q

What are the advantages and disadvantage of producing ethanol by hydration of steam and fermentation

A

Hydration - currently inexpensive, continuous process, pure product however uses crude oil a non-renewable source, requires lots of energy due to high T and P.

Fermentation - sugar is raw material which is renewable, conditions are inexpensive to produce so little energy required however batch process, slow reaction and impure product

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11
Q

In car engines nitrogen dioxide and nitrogen monoxide can be produced. Give equations for both

A

N2+2O2 -> 2NO2

N2+O2 -> 2NO

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12
Q

What are the causes, effects and ways of reducing acid rain

A

Causes: Emissions of SO2, NO2 and NO from burning fossil fuels dissolve in clouds, forming sulfurous, nitrous and nitric acid.

Effects: Trees and other vegetation dies. Crops die. Pond life dies due to lowering of pH. CaCO3 is chemically eroded and many metals are corroded.

Ways of reducing: Calcium carbonate (limestone) is dissolved in lakes to neutralise acid. Scrubbers are installed in factories to remove S02 from emissions. Catalytic converters in vehicle engines split NO into N2 and O2.

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13
Q

In order, what are the fractions required to be known for the IGCSE EdExcel Chemistry Exam? What are their uses?

A
  1. Refinery Gases (domestic heating and cooking)
  2. Gasoline (petrol for cars)
  3. Kerosene ( Jet fuel)
  4. Diesel Oil or gas oil (fuels for large engines - buses, lorries)
  5. Fuel Oil (fuel for ships engines, industrial heating)
  6. Bitumen (resurfacing roads)
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14
Q

How does fractional distillation work?

A

Crude oil (mixture of hydrocarbons) is heated until it vaporises in a furnace. It is then passed into a fractioning column. The longer chained hydrocarbons have a higher boiling point and remain at the bottom. The opposite is true for the short chained hydrocarbons which rise up the column until they cool and condense. Each ‘fraction’ is siphoned away.

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15
Q

What is the purpose of cracking?

A

To produce short chain hydroxarbons that are in high demand from long chain hydrocarbons that have a lower demand

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16
Q

Describe the process and conditions of cracking

A

The sample if heated over a silicon dioxide or aluminium oxide catalyst at around 600-700oC

17
Q

The products of a particular cracking process are C6H14 and C16H32. What is the formula of the hydrocarbon that was cracked?

A

C22H46

18
Q

A hydrocarbon C20H42 is cracked and one product has the formula C12H24. What is the formula of the other compound?

A

C8H18

19
Q

What type of reaction is cracking

A

Thermal Decomposition

20
Q

What are the uses of the following polymers: poly(ethene), poly(propene), Poly(chloroethene), polytetrafluoro(ethene)

A

poly(ethene) - milk jugs, detergent bottles, trash bins, plastic bags.

poly(propene) - food packaging, ropes, carpets.

poly(chloroethene) - Plastic sheets, artificial leather, drainpipes and gutters

polytetrafluoro(ethene) - non-stick frying pans

21
Q

Why are addition polymers hard to dispose of?

How is this different to condensation polymers?

A

They are chemically inert so do not easily break down or biodegrade. Often when they are burned they also produce toxic gases.

Some condensation polymers are able to biodegrade, they are known as biopolyesters.

22
Q

What are the two types of polymerisation? Describe what happens in each

A

Addition Polymerisation - monomers (often containing double bonds) join together to make a much larger molecule. The double bond breaks and this allow the monomers to form new bonds to other monomer molecules.

Condensation Polymerisation - monomers join together and a small molecule (normally water or HCl) is given off

23
Q

Give two examples of condensation polymers

A

Polyesters and polyamides (e.g. nylon)

24
Q

Define the following key terms: homologous series, hydrocarbon, isomerism

A

Homologous series- a group of compounds with the same functional group, differing by CH2, but with the same general formula, they have similar chemical properties and a trend in physical properties

Hydrocarbon - a compound that contains hydrogen and carbon only.

Isomer - molecules with the same molecular formula but a different structural formula

25
Q

What is crude oil?

A

A mixture of hydrocarbons

26
Q

Name the first six alkanes and alkenes

A

Alkanes: methane, ethane, propane, butane, pentane, hexane
Alkenes: ethene (there is no methene as two carbons are needed), propene, butene, pentene, hexene, heptene

27
Q

What is the equation for the substitution reaction of ethane and bromine?

Why is it a substitution reaction?

What condition is needed for the reaction to happen?

A

C2H6 + Br2 —–> C2H5Br + HBr

The bromine substitutes for one hydrogen, there are are two reactants and two products.

This reaction only happens when UV light is present.

28
Q

Describe the trend in colour, viscosity and boiling point for the fractions of crude oil (in order of increasing carbon chain length),

A

As chain length increases…
The colour gets darker
The viscosity gets higher
The boiling point gets higher

29
Q

Acid rain can be caused by sulfur dioxide emissions, what is the cause of this?

A

Fuels often contain sulfur impurities which can react with oxygen in car engines to form sulfur dioxide which leads to acid rain.

30
Q 
What is the functional group present in each of these homologous series:
Alkanes
Alkenes
Alcohols
Carboxylic Acids
Esters
A 
Alkanes - no functional group
Alkenes - C=C (carbon-carbon double bond)
Alcohols - COH
Carboxylic Acids - COOH
Esters - COOC
31
Q

What common carboxylic acid is found in vinegar?

A

ethanoic acid

32
Q

What are the common uses of ester and why?

A

Esters are often used for flavourings and perfumes as they have distinctive smells and are volatile

33
Q

What is the general equation for the formation of an ester?

A

Carboxylic acid + alcohol —> ester + water

In the presence of an acid catalyst

34
Q

Name the alcohol and carboxylic acid that would form the following esters:

ethyl propanoate

methyl ethanoate

A

ethyl propanoate formed from
ethanol
propanoic acid

methyl ethanoate formed from
methanol
ethanoic acid

(try drawing them)

35
Q

Name the first four carboxylic acids:

A

methanoic, ethanoic propanoic and butanoic

Try drawing them to test yourself more

Edexcel IGCSE Chemistry (4 decks)

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