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Chemistry Year 12 > module 4.2 > Flashcards

module 4.2 Flashcards

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1
Q

what’s the general formula of alcohols

A

CnH2n+1OH

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2
Q

how does chain length affect boiling point in alcohols and why

A

longer = hugger bp

more london forces
more surface contacts
more energy needed to over come

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3
Q

why is an alcohols bp higher than alkanes and alkenes

A

has an O which can hydrogen bond

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4
Q

when is it easier to hydrogen bond with alcohols

A

smaller molecules because there is closer proximity

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5
Q

what are alcohols solubility and why

A

soluable because they can hydrogen bond - more successful with shorter chain

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6
Q

what are the voltilities of alcohols and why and the trends

A

quite low, because of their tendency to form hydrogen bonds, decrease in volatility the more OH (tendancy to hydrogen bond)

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7
Q

what’s the trend in viscosity with alcohols

A

the more OHs the more viscous

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8
Q

what is a primary alcohol

A

has the functional group attached to a carbon atom with no more than one alkyl group

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9
Q

what is a secondary alcohol

A

has the functional group attached to a carbon atom with two alkyl groups

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10
Q

what is a tertiary alcohol

A

has the functional group attached to a carbon atom with three alkyl groups

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11
Q

what is reflux

A

the constant boiling and condensing of a reaction mixture to ensure that the reaction goes to completion as fully as possible without losing reactants or products as vapour to the air

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12
Q

what is a common oxidising agent

A

K2Cr2O7/H+

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13
Q

what is the product of primary alcohol oxidation

A

distillation: aldehyde and 1H2O
reflux: carboxylic acid and 1H2O

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14
Q

what’s the product of oxidation of a secondary alcohol

A

reflux: ketone + H2O

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15
Q

what’s the product of the oxidation of a tertiary alcohol

A

doesn’t oxidise so nothing

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16
Q

what’s the colour change of potassium dichromate when it oxidises

A

orange —> green

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17
Q

what does immiscible mean

A

insoluble

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18
Q

what reagents does esterification need

A

sulphuric acid

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19
Q

what are the reagents and conditions of dehydrating alcohols

A

concentrated H2SO4 reflux at 170°C

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20
Q

in esterification, where do the OH and H come from

A

OH from acid H from alcohol

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21
Q

how do you name esters

A

alcohol-yl acid-anoate

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22
Q

equation for halide substitution

A

ROH + HX —> RX + H2O

23
Q

what does halide substitution of an alcohol create

A

a haloalkane

24
Q

what reagents does halide substitution need

A

hydrogen halide, concentrated H2SO4

25
Q

what acid catalyst is used for iodide substation

A

phosphoric acid

26
Q

what is dehydration

A

a chemical reaction in which water molecules are eliminated from an organic compound

27
Q

what is elimination

A

an organic reaction in which one reactant forms two products

28
Q

what’s a nucleophile

A

an electron pair donor

29
Q

why are are haloalkanes reactive

A

the electron deficient delta+ centre is susceptible to attack by nucleophiles

30
Q

common nucelophiles

A

OH-
NH3
CN- (cyanide ion)

31
Q

what must you remember when showing nucleophillic substitution

A

backside attack, must go in the place it comes in, always show the booted out product

32
Q

how do you turn haloalkanes into alcohols

A

hydrolysis under reflux by nucleophillic substitution using water or aqueous alkalai

33
Q

what affects rate of hydrolysis of haloalkanes

A

the strength of the C-X bond and polarity of the bond - BUT bond strength is more important

34
Q

what’s the trend of rate of hydrolysis with haloalkanes

A

increases down the grouo

35
Q

what is nucleophilic substitution

A

a chemical reaction in which an atom or group of atoms is exchanged for a nucleophile

36
Q

what does ozone absorb

A

all UV-C and most UV-B radiation

37
Q

what is a radical

A

a highly reactive species with one or more unpaired electrons

38
Q

why are CFCs bad

A

the C-Cl bond undergoes homolytic fission under UV light
C2F2Cl2 —> C2F2Cl• + Cl•
the Cl• decomposes ozone

39
Q

show the propagation steps and overall equation of the destruction of ozone by chlorine radicals

A

Cl• + O3 —> •ClO + O2
•ClO + O3 —> Cl• + 2O2
overall O3 —> O2

40
Q

show nitrogen oxide decomposing ozone

A

•NO + O3 —> •NO2 + O2
•NO2 + O —> •NO + O2
overall: O3 + O —> 2O2

41
Q

what flask do you use for distillation

A

round bottomed flask

42
Q

what flask should you use for reflux

A

pear shaped

43
Q

how to use a separating funnel

A

clamp an iron ring and put the separating funnel in it
remove the stopper and make sure that the tap at the bottom is closed
pour mixture into funnel til no more than half full
wash reaction vessel with water and add to funnel - still leaving some air
put stopper back on
pick up funnel and invert it
open tap to equalise pressure
repeat until no whistle
put back in iron ring and leave to separate into layers
remove stopper and open the tap with a beaker underneath
collect the lower aqueous layer in the beaker and discard
get a new beaker and open the tap to collect desired organic product
shake with a drying agent and pour final dry product into new container

44
Q

drying agent examples

A

inorganic anhydrous salts
MgSO4 and CaCl2

45
Q

how to use drying agents

A

add drying agent
if it clumps together add more
when it remains free moving the mixture is dry
filter to collect the dry organic product

46
Q

what is a separating funnel

A

a piece of equipment used to separate immiscible liquids

47
Q

what is redistillation

A

the purification of a liquid using multiple distillations

48
Q

what has more than one functional group

A

aspirin carboxylic acid and benzene ring

niacin carboxylic acid and pyridine ring

49
Q

how do molecules reaction to infrared radiation

A

they absorb it and it makes the covalent bonds vibrate more in a stretching or bending motion

50
Q

what does a covalent bond vibration frequency depend on

A

bond strength
bond length
mass of each atom involved in the bond

51
Q

what to remember when reading an infrared spectroscopy graph

A

give range from sheet not specific
mention peaks that aren’t there!!
random bits under 1000 are usually from interference from solution
to check if a peak is b-road look at the top
a strong peak is around 50 and over

52
Q

how does mass spectrometry work

A

organic compound vaporised and driven through a mass spectrometer, some molecules lose an electron and because ionised (1+ ion)
mass of lost electron is negligible

53
Q

what is the tiny M+1 peak for

A

the presence of isotopes

54
Q

pros and cons of mass specra

A

uses small quantities so is relatively cheap
is a destructive analytical technique and the sample can’t be reclaimed after analysis

Chemistry Year 12 (7 decks)

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