Organic Chemistry-PAPER2 Flashcards

1
Q

What is an alkane?

A

A hydrocarbon that is only made up of single bonds

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2
Q

Give some properties of alkanes.

A

All insoluble in water

Don’t react with water or other aqueous solutions.

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3
Q

What is an alkene?

A

A hydrocarbon made up of double bonds.

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4
Q

Alkenes are more…… than alkanes

A

reactive.

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5
Q

What happens to alkenes in a large amount of oxygen?

A

Combust completely into only water and carbon dioxide.

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6
Q

Alkenes burn with a …….

A

smoky flame.

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7
Q

What is an addition reaction?

A

Where the double bond will open up to leave a single bond meaning a new atom is added to each carbon.

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8
Q

What froms from the reaction of steam and an alkene?

A

Alcohol, it can then be purified via fractional distillation.

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9
Q

How can you test an alkene?

A

Bromine water and an alkene in a sealed flask, after shaking it(otherwise they won’t mix) the mixture should become colourless.

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10
Q

What are plastics made up of?

A

Long chain molecules called polymers.

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11
Q

What is a polymer?

A

Large molecule formed when lots of monomers join together.

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12
Q

Give the balanced equation for the complete combustion of ethanol, C2H5OH

A

C2H5OH+302—-> 2CO2+3H20

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13
Q

What, in a compounds name, tells you it has a double bond?

A

ENE

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14
Q

What is the order of the first 4 alkenes?

A

Ethene- Eat (2 Carbons) ethene is the first alkene
Propene- Purple (3 Carbons)
Butene-Bananas (4 Carbons)
Pentene- Please (5 carbons)

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15
Q

Describe the combustion of an alkene compared to an alkane?

A

An alkene will burn with a smokier yellow flame, it will be an incomplete combustion and it will release less energy per mole in combustion than alkanes.

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16
Q

What makes alkenes more reactive than alkanes?

A

Their C=C double bond, as it is electron dense and the double bond can open up and other molecules can react with the carbons (addition reaction)

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17
Q

Members of a homologous series all have the same…

A

Members of a homologous series all have the same functional group (e.g. carbon to carbon double bond)

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18
Q

What are some advantages and disadvantages of hydrogenation.

A

Straightens the molecules (less healthy as they are more tightly packed together)
Increases the melting point.

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19
Q

What happens to the structure of an alkene during the homologous series?

A

After each molecule, an extra carbon atom is gained and 2 hydrogen atoms are gained.

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20
Q

What is the general chemical formula for alkenes?

A

C(n)H(2n)

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21
Q

What does combustion mean?

A

Combustion means burning

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22
Q

What happens during the combustion of an ALKANE?

A

When we combust alkanes we produce Carbon Dioxide and water. This is also true for ALKENES.

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23
Q

What happens when combusting an alkene that doesn;t happen to an alkane?

A

Combusting an alkene also proudces unburnt carbon particles. That is because of incomplete combustion and results in alkenes burning in air with a SMOKEY FLAME.

24
Q

What happens when you react an alkene with hydrogen?

A

You produce an alkane.

25
Q

What tells us that all of the alkenes react in the same way?

A

Alkenes have the same functional group (carbon double bond) which means that they are react in the same way.

26
Q

What is hydration?

A

The reaction of an alkene with water (steam) to produce an alcohol.

27
Q

Describe the conditions needed to make ethanol?

A

300”c and at 70atm.(reversible reaction) We used phosporic acid as a catalyst to speed up the reaction
Ethene + H2O(steam) ethanol

28
Q

How would you increase the yield of ethanol?

A

Any unreacted ethene and steam are passed back through the catalyst as it is reversible

29
Q

Describe the process of Ethene reacting with a halogen (chlorine)

A

Ethene + Chlorine(Cl2) —> dichloroethane

(The chlorines have been added to the carbon and the carbon to carbon double bond has broken, resulting in the molecule becoming an alkane)

30
Q

Name 2 products which are produced during incomplete combustion that aren’t produced from complete combustion.

A

Carbon monoxide and carbon are produced during an incomplete combustion but NOT complete.

31
Q

What is a functional group?

A

A group of atoms in a molecule that determine how that molecule typically reacts.

32
Q

What happens to the molecule during an addition reaction?

A

The Carbon to carbon double bond will open up to leave a single bond and a new atom is added to each carbon.

33
Q

In the name “dibromoethane”, what determines the “di”?

A

The number of particular atoms in this case of Bromine, there are 2 so its “di”

34
Q

What are the first four alcohols and what similar properties do they have?

A

Methanol, Ethanol, Propanol and Butanol are all soluble in water. Their solutions have a neutral pH.

35
Q

When alcohols are oxidised by reacting with oxygen (e.g. from the air) they produce…..

A

When alcohols are oxidised by reacting with oxygen they produce Carboxylic Acid.

36
Q

What are alcohols such as methanol and ethanol used for?

A

Methanol and ethanol are sometimes used as solvents in industry as they can dissolve most things water can dissolve as well as things water can’t e.g. hydrocarbons oils and fats.

37
Q

What are the first four alcohols generally used for?

A

The first 4 alcohols are generally used as fuels e.g. ethanol as a fuel in spirit burners, its burns fairly cleanly and it’s non-smelly.

38
Q

Ethanol is the alcohol found in…..

A

alcoholic drinks.

39
Q

How are alcoholic drinks made?

A

Alcoholic drinks are made using fermentation.

40
Q

What is fermentation?

A

Fermentation uses an enzyme in yeast to convert sugars into ethanol.
Sugar —–yeast—-> ethanol +carbon dioxide

41
Q

What temperature does fermentation generally happen fastest at?

A

37”c in a slightly acidic solution and under anaerobic conditions( no oxygen)

42
Q

What would happen to the enzyme in yeast if it wasn’t under it’s ideal conditions?

A

When yeast is in these ideal conditions it works best at converting sugar to alcohol. If these conditions were different the enzyme would be denatured or would work at a much slower rate. (e.g. lower pH and higher temperature).

43
Q

When alcohols react with an oxidising agent what do they produce?

A

A carboxylic acid and water

44
Q

What does the combustion of alcohols do?

A

The combustion of alcohols release energy

45
Q

What is the carboxylic acid functional group?

A

C=O
|
OH

46
Q

In water carboxylic acids are what?

A

In water carboxylic acids are weak acids,

47
Q

What is made when reacting a carboxylic acid with an alcohol?

A

A molecule called an Ester and water.

48
Q

Why are esters often useful molecules?

A

Esters often have a pleasant smell and therefore are used in food.

49
Q

What part of a molecules name tells you that it is a carboxylic acid?

A

…oic acid.

50
Q

What does viscosity mean?

A

Something with a high viscosity is thick and can’t flow very well (treacle), but if it has a low viscosity it is thin and easily flows (water)

51
Q

If a hydrocarbon has a long carbon chain what does that mean about it viscosity?

A

It will have a high viscosity (thickness)

52
Q

What is volatile?

A

low boiling point

53
Q

What does the length of the hydrocarbon mean about how volatile it is?

A

The shorter the chain the lower the boiling point.

54
Q

How does flammability depend of the length of the hydrocarbon?

A

The shorter the hydrocarbon the more flammable

55
Q

What is the formula for cracking?

A

Long chain hydrocarbon—> shorter alkane + alkene

56
Q

What is the cracking reaction?

A

A thermal decomposition reaction (breaking down molecules by heating them)

57
Q

What is cracking?

A

Producing smaller more useful alkane molecules from the longer alkane molecules produced from fractional distillation.