Organic Chemistry Flashcards

1
Q

What is crude oil?

A

Crude oil is a mixture of compounds; a fossil fuel consisting of the remains of ancient biomass.
Finite resource - cannot be replaced as it is used up

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2
Q

What is a hydrocarbon?

A

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

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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
  • 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 solids, 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
  • Vapour rises up the fractionating column
  • The column is hotter at the bottom and cooler at the top
  • 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 the bottom
  • Small molecules, low boiling points - collected at the top
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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 vapour, passed over a hot catalyst or heated to vapour, mixed with steam and heated to high temperatures

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11
Q

How are the products of cracking used?

A

The 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. Contains a C=C bond
General formula for alkenes is: 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

They burn with smoky flames due to incomplete combustion

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15
Q

Describe addition reactions of alkenes

A

Addition atoms across the carbon-carbon double bond so that the double bond becomes a single carbon-carbon bond
a) with hydrogen - requires a high temp and a nickel catalyst
b) with steam - requires a high temp and concentrated phosphoric acid as a catalyst
c) with Br2/Cl2/I2 - addition of halogens

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16
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
17
Q

What are some uses of alcohols?

A
  • Fuels
  • Solvents
  • Drinks
18
Q

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

A

30 degrees Celsius, aqueous solution of the glucose, absence of air, yeast added:
C6H12O6 –> 2CH3CH2OH + 2CO2

19
Q

What is a polymer? How do molecules containing C=C bond form polymers?

A

A polymer is a long chain molecule which is made by lots of smaller molecules joining together
C=C bonds open up and many smaller molecules join together to form a chain. No other products are made
It is called an addition polymerisation reaction

20
Q

Give 3 examples of addition polymers and their uses

A

Polyethene - plastic bags
polytetraflouroethene - non-stick kitchenware
Polychloroethene - water pipes