Module 4 Organic Chemistry Flashcards
1
Q
what does nomenclature mean?
A
It is the system used for naming organic compounds
2
Q
what is the empirical formula?
A
Simplest whole number ratio of atoms of each element in a compound
3
Q
what is the molecular formula?
A
the actual number of atoms of each element in a molecule
4
Q
what is the displayed formula?
A
shows the arrangement of every atom and every bond in a molecule
5
Q
what is the structural formula?
A
shows arrangement of atoms in a molecule without showing every bond
6
Q
what is the skeletal formula?
A
shows the bonds of the carbon skeleton only
each vertex is a carbon atom
with any functional groups
7
Q
what is a homologous series?
A
a series of organic compounds which have the same functional group and each successive member differs by CH2
8
Q
what is a functional group?
A
a group of atoms responsible for characteristic reactions of a compound
9
Q
what is the general formula?
A
An algebraic formula that can describe any member of a family of compounds
10
Q
what is an aliphatic hydrocarbon
A
contain carbon and hydrogen only joined in straight chains, branched chains or non-aromatic rings
11
Q
what is an alicyclic hydrocarbon?
A
hydrocarbons arranged in non aromatic rings with or without side chains
12
Q
what is an aromatic hydrocarbon?
A
contain at least 1 benzene ring
13
Q
what are the suffixes for:
alkane
allene
alcohol
aldehyde
ketone
carboxylic acid
A
-ane
-ene
-ol
-al
-one
-oic acid
14
Q
what are the prefixes for:
CH3 group
C2H5 group
C3H7 group
C4H9 group
Cl group
Br group
I group
A
methyl
ethyl
propyl
butyl
chloro
bromo
iodo
15
Q
what is the general formula of alkanes?
A
CnH2n+2
16
Q
what is the general formula of alkenes?
A
CnH2n
17
Q
what is the general formula of alcohols?
A
CnH2n+1OH
18
Q
what does saturated mean?
A
organic compounds containing only single bonds
19
Q
what are unsaturated compounds?
A
organic compounds that contain at least one C=C double bond
20
Q
what is a structural isomer
A
molecules with same molecular formula but different structural formula
21
Q
what are 3 ways in which structural isomers can be formed?
A
Alkyl groups can be in different places
functional groups bonded to different parts
different functional groups
22
Q
what are stereoismers
A
same molecular formula but have different arrangement of atoms in space
23
Q
what are E/Z isomers and how are they decided
A
E-Z isomers are caused by limited rotation around C=C
If 2 substituents with highest atomic number are on same side of double bond - Z
If they are in different side of the double bond - E
24
Q
what is Cis-Trans isomerism
A
type of E-Z isomerism where 2 substituents on each carbon atom are on same side
25
what is homolytic fission?
when each bonded atom receives one electron from bonded pair which forms 2 radicles
26
what is heterolytic fission?
when one bonded atom receives both electrons from the bonded pair forming an ion
27
what are radicals
highly reactive
neutral species
with an unpaired electron
28
what is a covalent bond formed between 2 radicals?
The radicals collide and the electrons are involved in the bond formation
29
what is an alkane?
A saturated hydrocarbon containing C-H bonds only
30
are alkane bond polar?
No
they are non polar because carbon and hydrogen have similar electronegativities
31
what is the shape and angle of an alkane?
tetrahedral
109.5°
32
describe the σ bond in an alkane
the sigma bond is the direct overlap of the electron clouds (2 s orbitals) of the bonding atoms
33
what type of intermolecular forces do alkanes have?
London forces
induced dipole-dipole because they are nonpolar
34
what happens to boiling point as alkane chain length increases
boiling point increases as there is a higher surface area so more induced dipole-dipole interactions (greater london forces) so more energy required to break bonds
35
does a branched molecule have a higher or lower boiling point?
branched chains have a lower boiling point because they have less surface area (fewer points of contact) so have less induced dipole-dipole interactions (weaker london forces)
36
are alkanes soluble in water?
No
They are insoluble
because hydrogen bonds in water are stronger than London forces in alkanes
37
how reactive are alkanes?
Very unreactive
strength of C-H bond and C-C bond hard to overcome
38
what reactions will alkanes undergo?
combustion - CH4 + 2O2 —> CO2 + 2H20
reaction with halogens-
CH4 + Br2 —> CH2BR2 + H2
39
what type of reaction is combustion?
oxidation
40
what is complete combustion
combustion that occurs with an excess of oxygen
41
what are the products of combustion?
carbon dioxide + water
42
what is the colour of the bunsen burner during complete combustion
blue
(roaring flame)
43
what is incomplete combustion
Combustion in limited supply of oxygen
C2H6 + 3O2 —> CO + CO2 + 3H20
44
write equation for complete combustion of propane
C3H8 + 502 —> 3CO2 + 4H20
45
what type of hydrocarbon is more likely to undergo incomplete combustion
longer chains
require more O2 to fully oxidize
46
what is the environmental impact of CO
toxic/poisonous
binds to hemoglobin in red blood cells and replaces O2
47
what is the environmental impact of soot (C)
smog
asthma
cancer
48
how are haloalkanes formed from alkanes?
free radical substitution
using UV light
49
what are the 3 stages of radical substitution?
Initiation - breaking of a halogen bind forms 2 free radicals
Propagation 1 + 2 - chain part of reaction where products are formed but free radicals remain
Termination - free radicals react and are removed stable products remain
50
CH4 + Cl2 —> CH3Cl
Initiation: Cl2 —> Cl. + Cl.
Propagation 1:
CH4 + Cl. —> CH3. + HCl
Propagation 2:
CH3. + Cl2 —> CH3Cl + Cl.
Termination:
Cl. + Cl. —> Cl2
CH3. + CH3. —> C2H6
CH3. + Cl. —> CH3Cl
51
what are alkenes?
Unsaturated hydrocarbons that contain at least 1 C=C made up of a σ bond and a π bond
52
how is a π bond formed?
electrons in adjacent p orbitals overlap above and below the carbon atoms
can only be made after σ bond forms
53
what bond restricts rotation of carbon atoms
π bond
54
what is the angle and shape of an alkene?
Trigonal planar
120°
55
Are alkenes more or less reactive than alkanes?
More reactive
due to high electron density of double bond and the π bond is easier to break
56
what intermolecular forces of attraction do alkenes have?
Only London forces
due to nonpolar bonds
57
Are alkenes soluble in water ?
No
as they have Non-polar bonds
58
write the equation for the complete combustion of Pent-2-ene
CH3CH=CHCH2CH3 + 15/2 O2 —> 5CO2+ 5H20
59
what are the types of isomers that can be formed using alkenes?
E/Z liners due to restricted rotation around C=C
Cis-Trans isomers- if 2 of the same substituents are attached to each carbon
60
what is an electrophile?
species that are electron pair acceptors
e.g Br2, H+
61
what is the most stable type of carbocation?
3°>2°>1°
alkyl groups have a positive inductive effect, so the most stable carbocation is the one bonded to the most other carbon atoms = Tertiary carbocation
62
which kind of carbocations form major products?
The most stable carbocation
(tertiary)
63
what conditions are needed for electrophilic addition of H20 to an alkene
steam (H20) 300°C
H3PO4 catalyst
hydration
alkene —> alcohol
64
what is the mechanism for the addition of water to ethene
CH2=CH2
curly arrow from C=C to H+
CH3CH2
+ on C, curly arrow from lp on O to C+
CH3CH2O
+ on O curly arrow from H to O+
to form CH3CH2OH
65
what conditions are needed for the electrophilic addition of a hydrogen halide to an alkene?
hydrogen halide gases must be at room temperature (298k)
66
mechanism for HBr + ethene
CH2=CH2
curly arrow from C=C to H, curly arrow from H to H-Br bond
CH3CH2
+ on C, curly arrow from :Br- to C+
to form CH3CH2Br
67
what is the reaction called when a halogen is added to alkene
halogenation
68
how does a molecule with a non-polar bond react as if it is an electrophile
C=C double bond with a high electron density induces a temporary dipole in the halogen molecule —> δ+ atom is attracted to the double bond
69
how can an alkene be converted to an alkane?
+ H2
Ni catalyst
150°C
hydrogenation
70
what is an addition polymer
many monomers bonded together via rearrangement of bonds without the loss of any atom or molecule
71
what are monomers
molecules which combine to form polymers
usually have C=C bond which breaks to leave a repeating pattern
72
how would you represent polymerization of ethene
n CH2=CH2 —> -[-CH2CH2-]- n
73
what are the ways that plastic can be disposed? (6)
- Landfill
- Organic feedstock
- Combustion
- To generate electricity
- Reuse
- Recycle
74
disadvantages of recycling
- plastics must be sorted into different types
- expensive
- labour intensive
- requires high technology
75
how does photodegradable polymers break down?
They are broken down chemically using energy with wavelengths similar to light. Once the break down begins it is not possible to stop the process
76
explain what happens in organic feedstock
plastics are separated and broken down into smaller, more useful components that can be further processed into plastics, fuels, polymers, and other products
77
what is a disadvantage of photodegradable polymers
may not be exposed to sufficient light
78
what is the functional group of an alcohol
OH- hydroxyl group
79
how do you name an alcohol
prefix + suffix
Hydroxyl-
-ol
80
what kind of intermolecular forces do alcohols have
hydrogen bonding
due to the difference in electronegativity in the OH bond
81
how do the melting point and boiling point of alcohols compare to other hydrocarbons of similar chain length
Higher
because they have hydrogen bonding ( strongest type of intermolecular forces) which is stronger than London forces
82
Are alcohols soluble in water?
Soluble in short chains - OH forms hydrogen bonds with water molecules
Insoluble in longer chains - C-H bond is non-polar
83
what makes an alcohol primary
C-OH is only bonded to one other Carbon atom
84
what makes an alcohol secondary
C-OH is bonded to 2 other carbon atoms
85
what makes an alcohol tertiary
C-OH is bonded to 3 other carbon atoms
86
what is the equation for the combustion of ethanol
C2H5OH + 3O2 —> 2CO2 + 3H20
87
what forms if you partially oxidize a primary alcohol
aldehyde
CH3CH2OH + [O] —> CH3CHO + H20
88
what conditions do you need to partially oxidize a primary alcohol
Dilute sulphuric acid
Acidified K2Cr2O7 (VI)
Distill product as it’s produced using gentle heat
89
what forms when you fully oxidize a primary alcohol?
carboxylic acid
CH3CH2OH + 2[O] —> CH3COOH + H20
90
what conditions are needed to fully oxidize a primary alcohol
Concentrated H2SO4
potassium dichromate (VI)
reflux - strong heating
91
what forms when you oxidize a secondary alcohol
ketone
CH3CH(OH)CH3 +[O] —> CH3COCH3 + H20
92
what conditions are needed to oxidize a secondary alcohol
concentrated H2SO4
potassium dichromate (VI)
strong heating
93
can you oxidize a tertiary alcohol
no
The carbon in C-OH isn’t bonded to a H atom which is needed to form the H20 molecule
94
what is a dehydration reaction
A reaction were water is lost to form an organic compound
95
what are the products of a dehydration reaction
alcohol —> alkene + water conditions:
reflux
c. H2SO4/ c. H3PO4
170°C
96
what are the products of the halide substitution reaction with alcohol
haloalkane + water
97
In what form is the halide used in halide substitution reaction
In the form of hydrogen halide
e.g
HBr
HCl
HI
98
how is a hydrogen halide made
A salt reacts with an acid to form the hydrogen halide
e.g NaBr + H2SO4 —> NaSO4 + HBr
when iodine is reacted H3PO4 is used as H2SO4 oxidizes iodine ions into iodine
99
what are haloalkanes
saturated organic compounds that contain carbon atoms and at least one halogen atom
100
are halogen alkanes soluble in water?
Insoluble as C-H bonds are non-polar not compensated for enough by C-X bond polarity
101
do haloalkanes have a polar bond?
Yes the halogen is more electronegative than C
the halogen is δ-
the carbon is δ+
102
what type of intermolecular forces do haloalkanes have?
Permanent dipole-dipole and London forces of attraction
C-X bond polarity creates permanent dipoles
103
when would haoalkanes have higher boiling points
as the carbon chain increases
or if the halogen is further down group 7
104
how would the mass of the haloalkane compare with the mass of an alkane of the same chain length
Greater as
mass of halogen > mass of H
105
what is the most important factor in determining halogen reactivity
the strength of the C-X bond
106
what would bond polarity suggest the order of halogen reactivity would be
C-F would be the most reactive as most polar bond
107
what would bond enthalpies suggest the order of reactivity would be?
C-I would be most reactive as lowest bond enthalpy
108
what is a primary halogen
The halogen is present at the end of the chain
bonded to 1 other carbon
109
Define nucleophile
Electron pair donor
e.g :OH-, :NH3, :CN-
110
what is nucleophilic substitution
A reaction where a nucleophile donates a lone pair of electrons to δ+ C atom the δ- molecules is replaced by nucleophile
111
what is hydrolysis
A reaction where water is a reactant
112
what reactant often produces hydroxide ions for hydrolysis
water
113
what fission does water undergo to produce OH-
Heterolytic fission
114
what is the mechanism for the reaction between bromoethane and NaOH
CH3CH2Br
curly arrow from C-Br bond to Br
curly arrow from :OH- to C of C-Br
115
what are CFCs
Chloro-fluoro-carbons
which are haloalkanes containing Cl, F and C only (no H)
116
What is the problem with CFCs
Although they are unreactive under normal conditions they catalyze the breakdown of ozone in atmosphere via free radicle substitution
117
what is the main function of ozone layer
provides protection from harmful UV radiation
118
does ozone play a protection role in all layers of the atmosphere
no
in the troposphere (lowest layer) is contributes towards photochemical smog
119
how do CFCs break the ozone layer down
free radicle substitution
120
write an equation of the overall decomposition of ozone —> Oxygen
2O3 –> 3O2
121
write a free radicle substitution equation for ozone
Cl2 -> Cl. + Cl. (UV light)
Cl. + O3 —> ClO. + O2
ClO. + O3 —> 2O2 + Cl.
overall
2O3 —> 3O2
122
show how nitrogen monoxide can decompose ozone
.NO + O3 —> .NO2 + O2
.NO2 + O —> .NO + O2
overall
O3 + O —> 2O2
123
describe how a quick fit apparatus is connected
grease the joints using some petroleum jelly on the inside of the joints before connecting the pieces together
124
In a distillation setup why is it necessary to have a continuous water flow around the condenser
so the water remains cool in order for the mixture to be distilled
125
describe a method that can be used to separate immiscible liquids
- pour the mixture into a separating funnel and some distilled water
- Add the stopper and invert the flask to mix a mixture
- equalize the pressure by opening the stopper as required
- continue shaking until there is no ‘whistle’ sound
- to collect the water in lower layer, open tap and place a beaker under spout
- use another beaker to collect desired organic layer
- shake liquid with owen drying agent to remove any water
126
name 2 drying agents
calcium carbonate (CaCO3)
magnesium sulphate (MgSO4)
127
how do you use a drying agent?
- Add a drying agent to the organic product
- If the drying agent forms clumps and more until they move freely
- Use gravity filtration to collect the dry product
- filtrate is the product
128
what is redistillation
When a liquid is purified using multiple distillations
129
How can unsaturated hydrocarbons be tested
Add some bromine water
colour change orange to colourless
130
what is used to test for haloalkanes
silver nitrate, ethanol and water
chloro - white precipitate
bromo - cream precipitate
iodo - yellow precipitate
131
what are the 3 reagents that can be used to test for carbonyls (C=O)
Acidified potassium dichromate
Fehling’s solution
Tollens’ reagent
132
Observation when acidified potassium dichromate reacts with ketones and aldehydes
ketone - no change
aldehyde - colour change from orange to green
133
what are the observations when Fehling’s solution is reacted with ketones and aldehydes
aldehyde - dark red precipitate
ketone - no change
134
what are the observations when Tollens’ reagent is reacted with ketones and aldehydes
ketones - no silver mirror
aldehydes - silver mirror
135
what are the reagents that can used to test carboxylic acid
universal indicator - pH of weak acid
reactive metal - hydrogen effervescence
metal carbonate - carbon dioxide effervescence
136
what happens when a molecule absorbs infrared radiation
it makes the covalent bond vibrate more in a stretching or bending motion
137
what factors affect the amount of vibration of a bond
bond strength
bond length
mass of each atom in the bond
138
how does infrared spectroscopy work
every bond has a unique vibration frequency in the infrared region of the EM spectrum
Bond absorbs radiation that has the same frequency as their frequency of vibration
Infrared radiation emerged from a sample is missing the frequencies that have been absorbed - this information can be used to identify the compound’s functional group
139
what do the peaks on an infrared spectrum represent?
Absorbance of energy from the infrared radiation
140
what are the 2 peaks that must be present to identify a substance as carboxylic acid
broad peak - symmetrical at 2500-300cm-1 —> OH group
sharp peak at 1680-1750 cm-1
—> C=O group
141
what happens inside a mass spectrometer
- organic compound is vaporized and passed through the spectrometer
- some molecules lose and electron and form molecular ions
- excess energy from the ionization makes the bonds vibrate more
- vibrations causes bond to weaken
- molecular ion splits by fragmentation
142
what is the symbol of molecular ion
M+
143
Is fragmentation predictable?
No because it can happen anywhere in a molecule
144
In a mass spectrometry how is a molecular ion represented
It is the peak with the highest m/z ratio
145
The molecular mass of the molecular ion is equal to what
the relative molecular mass (mr) of the compound
146
will the molecular ion peaks of 2 isomers of the same compound be different?
same
147
what is the m/z value of CH3+
15
148
what is the m/z value of OH- from alcohol
17
149
what is the m/z value of C2H5+
29
150
what is the m/z value of C3H7+
43
151
what is the m/z value of C4H9+
57
152
what are the advantages of using mass spectrometry (2)
- cheap
- small quantities of sample required
153
what is the main disadvantage of using mass spectrometry
the same is completely destroyed
