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A-Level Chemistry > Topic 17- Further organic chemistry > Flashcards

Topic 17- Further organic chemistry Flashcards

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1
Q

Define chiral

A

an atom in a molecule that allows it to exist as non-superimposable forms. it can also refer to the molecule itself

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2
Q

Give an example of something that shoes chirality

A

your hands- made of the same thing and a mirror image of each other but will not line up when placed on top of one another

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3
Q

Define asymmetric in terms of carbon atoms

A

refers to a carbon atom in a molecule that is joined to 4 different atoms or groups

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4
Q

What are enantiomers?

A

isomers that are related as object and mirror image

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5
Q

When does a substance show optical activity?

A

if it rotates the plane of polarisation of plane-polarised light

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6
Q

Define plane-polarised light

A

monochromatic light that has oscillations in only one plane

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7
Q

Define unpolarised light

A

has oscillations in all planes at right angles to the direction of travel

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8
Q

What is a polarimeter?

A

the apparatus used to measure the angle of rotation caused by a substance

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9
Q

Define a polariser

A

a material that converts unpolarised light into plane-polarised light

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10
Q

What is an analyser?

A

a material that allows plane-polarised light to pass through it

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11
Q

What is a racemic mixture?

A

an equimolar mixture of 2 enantiomers that has no optical activity

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12
Q

What is the functional group of carboxylic acids and their suffix?

A

COOH

-oic acid

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13
Q

What is the general formula of a carboxylic acid?

A

RCOOH

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14
Q

Which 2 groups maker up a carboxylic group?

A

carbonyl and hydroxide

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15
Q

Which carboxylic acids are soluble in water and why?

A

shorter chain carboxylic acids because they form hydrogen bonds with the water

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16
Q

What is the trend of solubility in carboxylic acids?

A

solubility decreases with chain length

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17
Q

What is the trend of boiling points in carboxylic acids?

A

longer chain= higher boiling point because there are more intermolecular (hydrogen) bonds

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18
Q

What is a dimer?

A

a double molecule

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19
Q

Which carboxylic acids form dimers?

A

shorter-chain carboxylic acids form dimers in the absence of a solvent e.g. water

20
Q

State the characteristics of carboxylic acids (taste and smell)

A

unpleasant and distinctive smells with sour tastes

21
Q

What is the bonding of carboxylic acids like?

A

most bonding occurs through a lost H+ atom to form a carboxylate ion, COO-

22
Q

How many polar bonds are present in carboxylic acids?

A

3 polar bonds

23
Q

What is a carbonyl group?

A

C=O

24
Q

Give 3 molecules with a carbonyl group

A
  • aldehydes
  • ketones
  • carboxylic acids
25
Q

What suffix do aldehydes have?

A

-al

26
Q

What suffix do ketones have?

A

-one

27
Q

What is the general formula of an aldehyde?

A

RCHO

28
Q

What is the general formula for ketones?

A

RCOR’ (‘meaning that the 2 hydrocarbon chains may differ)

29
Q

What is a C=C composed of?

A

a pi and sigma bond

30
Q

Is the C=C polar?

A

no because there are 2 identical carbon atoms involved with the same electronegativity

31
Q

Is the C=O polar?

A

yes because of the differing electronegativities of the electronegativities of oxygen and carbon so electron density is unevenly distributed

32
Q

What are the products of acyl chlorides and water?

A

vigorous reaction forming carboxylic acid and hydrogen chloride gas (misty fumes)

33
Q

What are the products of acyl chlorides and alcohols?

A

ester and hydrogen chloride gas

34
Q

What are the products of acyl chlorides and concentrated ammonia solution?

A

amide (-NH2 functional group) and hydrogen chloride gas further reaction occurs to form ammonium chloride

35
Q

What are the products of acyl chlorides and an amine?

A

a substituted amide and hydrogen chloride

36
Q

State the physical properties of esters

A
  • colourless liquids
  • low melting and boiling temperatures
  • insoluble in water (all hydrogen atoms in their molecules are attached to carbon atoms so H bonding impossible)
37
Q

What is heating under reflux used for?

A

reactions that are slow at room temperature

38
Q

Give details on heating under reflux process

A
  • flask is fitted with a reflux condenser because heating can cause volatile compounds to escape
  • all the vapours rising from the reaction mixture during heating enter the condenser and change back to liquids and return to the flask so that the unreacted compounds can react
39
Q

How is the pear shaped flask heated during reflux?

A

using hot water or oil in a beaker heated by a Bunsen burner or by using an electric mantle

40
Q

What is simple distillation used for?

A

to obtain a liquid product from a reaction mixture

41
Q

When is simple distillation used?

A

when there is a mixture with 2 liquids that have very different boiling temperatures (difference of more than 25 degrees)

42
Q

What is fractional distillation used for?

A

to separate multiple compounds in a liquid with smaller differences in boiling temperatures

43
Q

What are the beads and broken glass used for in fractional distillation?

A

column of beads or broken glass before the condenser which act as surfaces on which the vapour leaving the column can condense, and evaporated again when more hot vapour passes up the column

44
Q

What is steam distillation used for?

A

to separate an insoluble liquid from an aqueous solution

45
Q

What is the colour change when acidified potassium dichromate oxidises an aldehyde?

A

orange solution –> green solution

46
Q

What is the colour change when Fehling’s solution or Benedict’s solution oxidises an aldehyde?

A

deep blue solution –> red precipitate

47
Q

What is the colour change when Tollen’s reagent oxidises an aldehyde?

A

colourless solution –> silver mirror

A-Level Chemistry (20 decks)

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