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Chemistry > WM > Flashcards

WM Flashcards

1
Q

Why are alcohols polar?

A

Because of the polarised O-H bond

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2
Q

Which bond type is stronger; Covalent or Hydrogen?

A

Covalent

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3
Q

Describe the trend in solubility as you increase the length of the carbon chain on an alcohol.

A

Solubility decreases due to the polarity of the O-H bond becoming less important to the molecule compared to the carbon chain.

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4
Q

Give the definition for a primary alcohol

A

-OH bonded to a carbon bonded to one other carbon atom

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5
Q

Give the definition for a secondary alcohol

A

-OH bonded to a carbon bonded to two other carbon atoms

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6
Q

Give the definition for a tertiary alcohol

A

-OH bonded to a carbon bonded to three other carbon atoms

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7
Q

What colour change would we see when an acidified dichromate ion is used to oxidise an alcohol group

A

orange to green

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8
Q

Give the conditions required to go from ethanol to ethanal

A

Oxidation with potassium dichromate with the alcohol in excess (no reflux)

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9
Q

Give the conditions required to go from ethanol to ethanoic acid

A

Oxidation with potassium dichromate with the Oxidising agent in excess under reflux

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10
Q

When under reflux, what is the maximum height the vapour should condense at in the condenser?

A

halfway up

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11
Q

What colour would potassium dichromate be when added in excess to 2-methylpropan-2-ol and refluxed

A

Remains orange because 2-methylpropan-2-ol will only oxidise once to form the ketone.

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12
Q

What conditions are required for the dehydration for alcohol to the alkene

A

aluminium oxide catalyst at 300 degrees

or

refluxed with conc. sulfuric acid

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13
Q

What conditions are required for the esterification of an alcohol with a carboxylic acid

A

HCl catalyst heated under reflux

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14
Q

Give the three compounds we find an OH group in organic chemistry

A

Phenol
Carboxylic Acid
Alcohol

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15
Q

What ion is formed that makes -OH groups acidic

A

Hydronium ion (H3O)+

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16
Q

Put the following in order of increasing acidity
(low to high):
Phenol, Water, Ethanol, Carboxylic acid

A
  1. ethanol
  2. water
  3. phenol
  4. carboxylic acid
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17
Q

How could you determine the identities of 3 unknown samples of ethanol, phenol and ethanoic acid?

A

ethanoic acid will fizz when it reacts with Sodium carbonate and release carbon dioxide gas
phenol will turn purple with Iron(III) Chloride
ethanol could be identified by discolouration of acidified potassium dichromate

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18
Q

Describe the changing effect of the -OH group on a HC chain

A

Alcohol molecules are polar. As a hydrocarbon chain gets longer, the -OH group has less effect.

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19
Q

What is produced when an alcohol is dehydrated?

A

An alkene and water.

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20
Q

Describe 3 ways how esters are produced

A

Alcohol + carboxylic acid, strong acid catalyst, under reflux.
Acid anhydride + alcohol.
Phenol + acid anhydride

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21
Q

Describe trends in carboxylic acids, phenols and alcohols.

A

Strength of acids: ethanol, water, phenol, carboxylic acid.

Carboxylic acids make carbonates fizz, phenols and alcohols do not.

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22
Q

Describe the iron (III) chloride test.

A

The enol group of a phenol forms a purple complez with Fe3+.

23
Q

What is the process of mass spectrometry?

A

Ionisation, acceleration, deflection, detection.

24
Q

What are the principles of green chemistry? (12)

A 
Safer chemical products
Use safer solvents
Prevention of waste products
Energy usage
Reduce reagents
Catalysts
Atom economy
Real time process monitoring
Safer chemical processes

Less hazardous chemical synthesis
Design for degradation
Renewable feedstocks.

25
Q

What is the functional group of a carboxylic acid?

A

COOH

double bond to a oxygen and hydroxyl group

26
Q

What is the functional group of a phenol?

A

A benzene ring with a hydroxide group

27
Q

What is the functional group of an acid anhydride?

A

R-c-o-c-R
|| ||
O O

28
Q

What is the functional group of an Ester?

A

O
||
R-C-O-R

29
Q

What is the functional group of an aldehyde?

A

O
||
R-C-H

30
Q

What is the functional group of a ketone?

A

O
||
R-C-R

31
Q

What is the functional group of an ether?

A

R-O-R

32
Q

What two substances react with alkalis?

A

Phenols and carboxylic acid

33
Q

What do carboxylic acids react with that phenols don’t?

A

Carbonates

Not strong enough to remove hydrogen from phenol

34
Q

What is the test for phenols?

A

Adding iron (iii) chloride

Turns purple

35
Q

What can phenols react with that carboxylic acids can’t and what does it form?

A

Phenols react with acid anhydrides to form esters

36
Q

What forms what you oxidise a primary alcohol under distillation and what is the catalyst?

A

Aldehyde is formed

Catalyst is acidified potassium dichromate

orange –> green

37
Q

What forms what you oxidise a primary alcohol under reflux and what is the catalyst?

A

Carboxylic acid is made

Acidified potassium dichromate is used as a catalyst

orange –> green

38
Q

What forms when you oxidise a secondary alcohol under reflux?

A

A ketone is formed

orange –> green

39
Q

What happens when you oxidise a tertiary alcohol?

A

Nothing - remains orange

40
Q

Why do you need to use distillation to make an aldehyde?

A

You need to get it out of the oxidising solution as soon as it’s formed before it is further oxidised

41
Q

What can you also react with alcohol to produce an Ester?

A

Acid anhydride

More reactive and reacts completely on warming to give a much higher yield

Or carboxylic acid with concentrated HCl catalyst

42
Q

How can you form haloalkanes from alcohol?

A

Substitution reaction with halide ions

Strong acid

43
Q

What does vacuum filtration do?

A

Removes insoluble part of a mixture

44
Q

What do you use recrystilation to do?

A

Separate soluble parts of a mixture

45
Q

How do you choose the solvent used in recrystallisation?

A

Choose a solvent which the desired product is really soluble in when hot but in soluble when cool

46
Q

What is the M+peak?

A

The molecule in a sample is bombarded with electrons, this removes an electron from the molecule to form a molecular ion M+
The molecular job peak shows the molecular mass of the compound

47
Q

What is theM+1 peak caused by?

A

The presence of 13C isotope

48
Q

What are peaks on a mass spectrometry?

A

Due to positive ions and other fragments

49
Q

What happens when specific frequencies of infrared radiation act on a bond?

A

The bond in the organic molecule vibrates

50
Q

What are the steps of recrystallisation?

A

Dissolve the substance in hot solvent

Use the minimum amount of solvent

Filter hot solution to remove minimum amount of insoluble impurities

Allow to cool/ crystallise

Filter and wash with cold ethanol and dry in oven

51
Q

Give 4 reasons why recrystallisation can have a low percentage yield?

A

Loss of product when transferring between beakers

Reaction doesn’t go to completion

Some solid remains in solution after

Loss of solid when washing the final product

52
Q

how do you remove traces of water to purify?

A

add ahydrous sodium sulphate

53
Q

how do you remove acid traces?

A

add sodium carbonate and shake in a spearating funnel

Chemistry (6 decks)

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