organic chemistry (p2) Flashcards

1
Q

What is crude oil?

A

a mixture of a large number of compounds, most of which are hydrocarbon

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2
Q

How was crude oil formed?

A

from the remains of organisms that lived and died millions of years ago (mainly plankton which was buried in the mud)

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3
Q

Is crude oil a finite or renewable resource?

A

Finite

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4
Q

What is a hydrocarbon?

A

a compound made up of carbon and hydrogen only

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5
Q

Why type of bond joins the carbon and hydrogen atoms in a hydrocarbon

A

covalent bond

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6
Q

What is an organic compound?

A

compounds containing carbon atoms covalently bonded to other atoms

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7
Q

What is a homologous series?

A

a family of organic compounds with the same general formula and similar properities

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8
Q

What is the general formula for alkanes?

A

CₙH₂ₙ₊₂

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9
Q

What are the names of the first four members of the alkanes?

A

Methane
Ethane
Propane
Butane

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10
Q

What do the names of alkanes always end in?

A

-ane

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11
Q

How many bonds does carbon form in a compound?

A

four

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12
Q

How many bonds does hydrogen form in a compound?

A

1

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13
Q

How are the different compounds in crude oil separated?

A

Fractional distillation

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14
Q

What is a fraction?

A

a mixture of hydrocarbons with a similar number of carbon atoms

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15
Q

What are the products of fractional distillation used for?

A
  • fuels
  • starting materials for the petrochemical industry
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16
Q

What are the names of some fractions produced in fractional disillation?

A
  • petrol
  • diesel oil
  • kerosene
  • heavy fuel oil
  • liquefied petroleum gases
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17
Q

What useful materials are produced by the petrochemical industry?

A
  • solvents
  • lubricants
  • polymers
  • detergents
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18
Q

How does the temperature of the fractionating column change as you move from bottom to top?

A

the temperature decreases

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19
Q

What happens when crude oil is heated before entering the fractionating column?

A

the crude oil evaporates

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20
Q

What happens to the crude oil vapours as they travel up the fractionating column?

A
  • they cool and condense
  • when they condense they are collected
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21
Q

Describe how crude oil is seperated in fractional distillation

A
  • Crude oil is heated and it evaporates
  • The crude oil vapours enter the fractionating column and travel upwards
  • The temperature of the fractionating column decreases towards the top
  • As the vapours travel up they cool and condense at different temperatures depending on their boiling points
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22
Q

Where are the long chain hydrocarbons collected in fractional distillation?

A

At the bottom of the fractionating column

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23
Q

Where are the short chain hydrocarbons collected in fractional distillation?

A

At the top of the fractionating column

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24
Q

What causes the hydrocarbons to sepeate in fractional distillation?

A

They have different boiling points and so condense at different levels

25
Q

When will the hydrocarbons condense in the fractionating column?

A

When the temperature drops below their boiling point

26
Q

Why do short chain hydrocarbons collect at the top of the fractionating column?

A

They have low boiling points and so condense at lower temperatures

26
Q

Why do large chain hydrocarbons collect at the bottom of the fractionating column?

A

They have large boiling points and so condense at higher temperatures

27
Q

If a hydrocarbon boils at 300 ᵒC, what temperature will it condense at?

A

300 ᵒC

28
Q

What bonds break when hydrocarbons melt and boil?

A

Intermolecular forces

29
Q

What type of force holds hydrocarbon molecules together?

A

Intermolecular forces

30
Q

What does viscosity it mean?

A

How much a fluid resists flow (how gloopy it is)

31
Q

What does volatility mean?

A

How easy it is to turn a substance into a gas

32
Q

What does flammability mean?

A

How easy it is to ignite a substance

33
Q

As hydrocarbon molecules get bigger, what happens to their viscosity?

A

increases

34
Q

As hydrocarbon molecules get bigger, what happens to the boiling point?

A

increases

35
Q

As hydrocarbon molecules get bigger, what happens to their flammability?

A

decreases

36
Q

Why does the viscosity of hydrocarbons increase as the hydrocarbon molecules get bigger?

A

As the hydrocarbon molecules get bigger, the intermolecular forces get stronger and move over each other less easily

37
Q

Why does the boiling point of hydrocarbons increase as the hydrocarbon molecules get bigger?

A

As the hydrocarbon molecules get bigger, the intermolecular forces get stronger and require more energy to break

38
Q

Which are better fuels - long or short chain hydrocarbons?

A

Short chain (they are more flammable)

39
Q

What is combustion?

A

reaction with oxygen (burning)

40
Q

What is complete combustion?

A

burning in a plentiful supply of oxygen

41
Q

What are the reactants in complete combustion of a hydrocarbon?

A

hydrocarbon + oxygen

42
Q

What are the products in complete combustion of a hydrocarbon?

A

carbon dioxide + water

43
Q

What is cracking?

A

the breaking of longer chain hydrocarbons into shorter, more useful hydrocarbons

44
Q

Why do we ‘crack’ hydrocarbons?

A

to produce smaller, more useful molecules

45
Q

What is the reactant in cracking?

A

longer chain alkanes

45
Q

Why is cracking a thermal decomposition reaction?

A

the longer chain hydrocarbons breakdown when heated

45
Q

What are the products in cracking?

A

a shorter chain alk𝗮𝗻𝗲 and a short chain alk𝗲𝗻𝗲

45
Q

What is thermal decomposition?

A

the breakdown of a substance when it is heated

46
Q

Name two types of cracking

A
  • steam
  • catalytic cracking
47
Q

Describe the process of steam cracking

A
  • Long chain hydrocarbons are heated and they evaporate
  • The hydrocarbon vapour is heated to a very high temperature and mixed with steam
  • The hydrocarbons are broken into smaller hydrocarbons
48
Q

Describe the process of catalytic cracking

A
  • Long chain hydrocarbons are heated and they evaporate
  • The hydrocarbon vapour is then passed over a catalyst
  • The hydrocarbons are broken into smaller hydrocarbons
49
Q

[𝗛𝗶𝗴𝗵𝗲𝗿 𝘁𝗶𝗲𝗿] What is the general formula for alkenes?

A

CₙH₂ₙ

50
Q

Which are more reactive: alkanes or alkenes?

A

Alkenes

51
Q

What is used to test for alkenes?

A

bromine water

52
Q

What colour is bromine water?

A

orange

52
Q

What colour does bromine water turn when added to alkenes?

A

colourless

53
Q

What colour does bromine water turn when added to alkanes?

A

stays orange

54
Q

What are alkenes used for?

A

to make polymers and as the starting material when making many other chemicals