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Chemistry Year 12 > module 4.2 > Flashcards

module 4.2 Flashcards

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
what acid catalyst is used for iodide substation
phosphoric acid
26
what is dehydration
a chemical reaction in which water molecules are eliminated from an organic compound
27
what is elimination
an organic reaction in which one reactant forms two products
28
what’s a nucleophile
an electron pair donor
29
why are are haloalkanes reactive
the electron deficient delta+ centre is susceptible to attack by nucleophiles
30
common nucelophiles
OH- NH3 CN- (cyanide ion)
31
what must you remember when showing nucleophillic substitution
backside attack, must go in the place it comes in, always show the booted out product
32
how do you turn haloalkanes into alcohols
hydrolysis under reflux by nucleophillic substitution using water or aqueous alkalai
33
what affects rate of hydrolysis of haloalkanes
the strength of the C-X bond and polarity of the bond - BUT bond strength is more important
34
what’s the trend of rate of hydrolysis with haloalkanes
increases down the grouo
35
what is nucleophilic substitution
a chemical reaction in which an atom or group of atoms is exchanged for a nucleophile
36
what does ozone absorb
all UV-C and most UV-B radiation
37
what is a radical
a highly reactive species with one or more unpaired electrons
38
why are CFCs bad
the C-Cl bond undergoes homolytic fission under UV light C2F2Cl2 —> C2F2Cl• + Cl• the Cl• decomposes ozone
39
show the propagation steps and overall equation of the destruction of ozone by chlorine radicals
Cl• + O3 —> •ClO + O2 •ClO + O3 —> Cl• + 2O2 overall O3 —> O2
40
show nitrogen oxide decomposing ozone
•NO + O3 —> •NO2 + O2 •NO2 + O —> •NO + O2 overall: O3 + O —> 2O2
41
what flask do you use for distillation
round bottomed flask
42
what flask should you use for reflux
pear shaped
43
how to use a separating funnel
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
drying agent examples
inorganic anhydrous salts MgSO4 and CaCl2
45
how to use drying agents
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
what is a separating funnel
a piece of equipment used to separate immiscible liquids
47
what is redistillation
the purification of a liquid using multiple distillations
48
what has more than one functional group
aspirin carboxylic acid and benzene ring niacin carboxylic acid and pyridine ring
49
how do molecules reaction to infrared radiation
they absorb it and it makes the covalent bonds vibrate more in a stretching or bending motion
50
what does a covalent bond vibration frequency depend on
bond strength bond length mass of each atom involved in the bond
51
what to remember when reading an infrared spectroscopy graph
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
how does mass spectrometry work
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
what is the tiny M+1 peak for
the presence of isotopes
54
pros and cons of mass specra
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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