Module 4 - Chapters 11-13 P2 Flashcards
1
Q
what are organic compounds?
A
Any compounds containing carbon
2
Q
saturated hydrocarbons
A
single carbon-carbon bonds only (more saturated with hydrogen)
3
Q
unsaturated hydrocarbons
A
one or more carbon-carbon double or triple bonds (less saturated with hydrogen)
4
Q
compound with a triple bond
A
alkyne
5
Q
general formula of alkane
A
CnH2n+2
6
Q
general formula of alkyl
A
CnH2n+1
7
Q
general formula of alkene
A
CnH2n
8
Q
general formula of alcohol
A
CnH2n+1 OH
9
Q
general formula of carboxylic acids
A
CnH2n O2
10
Q
general formula of ketones
A
CnH2nO
11
Q
definition of homologous series
A
A series of organic compounds having the same functional group but with each successive member differing by CH2
12
Q
Functional group
A
part of the molecule largely responsible for the molecule’s chemical properties
13
Q
what functional group does an amine group have?
A
NH2
14
Q
name three classifications of hydrocarbons
A
aliphatic, alicyclic and aroMATic (not aroMANtic)
15
Q
aliphatic hydrocarbons
A
carbon atoms arranged in chains (branched or unbranched)
16
Q
alicyclic hydrocarbons
A
carbon atoms joined in a ring (cyclic) structure (branched or unbranched)
17
Q
aromatic hydrocarbons
A
some or all of the carbon atoms are found in a benzene ring (C6H6)
18
Q
general formula of alkyne
A
CnH2n-2
19
Q
general formula of cycloalkane
A
CnH2n
20
Q
prefix for naming carbon chain with 12 carbon atoms
A
Dodec
21
Q
prefix for naming carbon chain with 20 carbon atoms
A
Eicos
22
Q
functional group of aldehyde
A
CHO (O double bonded to C), functional group is always on carbon 1 for aldehydes
23
Q
suffix (ending) for aldehydes
A
-al
24
Q
functional group for ketones
A
C(CO)C (chain of 3 carbons and O double bonded to middle one)
25
suffix (ending) for ketones
-one
26
functional group for carboxylic acids
COOH (one O double bonded to C and one bonded as part of OH to carbon)
27
suffix (ending) for carboxylic acids
-oic acid
28
functional group for esters
COOC (one O double bonded to C, other O single bonded to two Cs)
29
suffix (ending) for esters
-oate
30
functional group for acyl chloride
COCl (O double bonded to C)
31
suffix (ending) for acyl chlorides
-oyl chloride
32
suffix (ending) for amines
-amine
33
functional group for nitriles
CN (N triple bonded to C)
34
suffix (ending) for nitriles
nitrile
35
molecular formula
shows the number and type of atoms of each element present in a molecule, doesn't show the bonding
36
definition for empirical formula
the simplest whole-number ratio of the atoms of each element present in a compound
37
displayed formula
shows the relative positioning of all of the atoms in a molecule and the bonds between them, each line represents a pair of shared electrons
38
structural formula
shows the arrangement of the atoms in a molecule by showing clearly which groups are bonded together
39
skeletal formula
a simplified organic formula with all of the carbon and hydrogen labels removed along with any bonds to hydrogen atoms, this just leaves a carbon skeleton and any functional groups
40
definition of structural isomers
molecules with the same molecular formula but different structural formula
41
what are the three types of structural isomers?
chain, positional, functional group
42
chain isomerism
when the carbon atoms are moved on the original carbon chain to form structural isomers
43
positional isomerism
when the basic carbon skeleton remains unchanged but important groups (such as functional groups) are moved around on that skeleton
44
functional group isomerism
when molecules containing different functional groups have the same molecular formula, functional groups can be changed (e.g. ketones/aldehydes)
45
what are the components of crude oil?
petroleum gases, petrol (gasoline), kerosene (paraffin), diesel, lubricating oil, heavy fuel oil, bitumen
46
use of petroleum gases
used in domestic fuel
47
use of petrol/ gasoline
cars
48
use of kerosene/ paraffin
aircraft
49
use of diesel
cars
50
properties of small molecules in crude oil
low bpt, light in colour, easy to ignite, not viscous
51
properties of large molecules in crude oil
high bpt, dark in colour, difficult to ignite, thick/viscous if liquid (bitumen = solid at room temp)
52
why does increase in chain length in hydrocarbons in crude oil increase bpt?
london forces increase because more electrons are present and increasing chain length increases surface contact
53
why does branching of alkanes decrease bpt?
- results in decreased points of surface contact between molecules so london forces decrease.
- branching also prevents molecules packing together as easily so molecules are further away and intermolecular forces decrease
54
what type of covalent bond bonds each carbon in an alkane?
sigma bonds ( σ) , formed by the overlapping of orbitals with each overlapping orbital containing one electron
55
why is it not possible for alkanes to have stereoisomers?
the sigma bond allows free rotation of atoms around the molecule
56
why do alkanes have a low reactivity?
- the sigma bonds are very strong (high bond enthalpy)
- C-C bonds are non-polar
- C-H bonds are considered non-polar due to the similar electronegativity of C and H
57
combustion
when alkanes react with oxygen to form carbon dioxide and water, heat is also produced
58
why are alkanes used as fuels?
- readily available
- easy to transport
- easy to burn in a plentiful supply of oxygen without releasing toxic products
59
composition of natural gas
typically 80% methane with varying proportions of ethane, propane and butane
60
alkane which is a component of petrol
heptane
61
incomplete combustion
in a limited supply of oxygen, hydrogen atoms always oxidised to water but carbon may form carbon monoxide or soot (soot = singular carbon atoms)
62
carbon monoxide
colourless, odourless, highly toxic
63
what are the two types of fission to break covalent bonds?
homolytic and heterolytic fission
64
homolytic fission
each of the bonded atoms takes one of the shared pair of electrons from the bond, each atom becomes a radical so the products are the same
65
radical
has a single unpaired electron
66
diradical
has two unpaired electrons
67
heterolytic fission
one of the bonded atoms takes both of the electrons from the bond, positive and negative ions are formed so the products are different
68
name three types of reactions
addition, substitution, elimination
69
addition reaction
two reactants join together to form one product
70
substitution reaction
an atom or group of atoms is replaced by a different atom or group of atoms
71
elimination reaction
the removal of a small molecule from a larger one, one reactant molecule forms two products
72
photochemical reaction
alkanes react with halogens in the presence of UV light because the UV provides the initial energy for a reaction to take place
73
name the stages of free radical substitution
initiation, propagation, termination
74
initiation
a chlorine molecule is broken down into 2 free radicals by homolytic fission, a superscript dot alongside an atom shows it is a radical (no dot required for diradical)
75
important point to remember about initiation
the products don't have to be the same element - just the same type of radical
76
propagation
chain reactions, one of the reactants and one of the products is always a free radical. always happens in two steps
77
propagation reactions to learn
CH4 + Cl' = CH3' + HCl
CH3' + Cl2 = CH3Cl + Cl'
(continued)
CH3Cl + Cl' = CH2Cl' + HCl
CH2Cl' + Cl2 = CH2Cl2 + Cl'
(or the chlorine radical in step 2 could react with methane again as in step 1)
78
termination
two radicals collide to form a molecule with all electrons paired, all free radicals are removed from the system
79
problems with free radical substitution
- further substitution can occur, may not result in the desired products
- position of substitution cannot be controlled so a mixture of mono-substituted isomers will be formed
80
how the products of further substitution can be controlled
using an excess of certain chemicals
81
why do alkenes have lower bpts than alkanes?
double bond puts a kink in the chain so the chains cannot pack together as closely (decreasing surface contact so decreasing london forces)
82
what is the other type of covalent bond (other than sigma) in alkenes?
pi bond, formed by the overlap of two p orbitals
83
why is the pi bond weaker than the sigma bond?
electrons are further from the nucleus in the pi bond
84
why can stereoisomers be formed with alkenes?
the pi bond restricts rotation of atoms around the molecule
85
key point about double bonds and drawing in 3D
only counts as one area of electron density
86
definition of stereoisomerism
when molecules have the same molecular and structural formulae but a different arrangement in space
87
types of stereoisomerism
E-Z, cis-trans
88
rules for E-Z isomerism
- must have a C=C double bond
| - different groups must be attached to EACH CARBON atom in the double bond
89
Z isomers?
groups (same or with highest priority) on the same side of the molecule
90
E isomers?
groups (same or with highest priority) on different sides of the molecule
91
rules for cis-trans isomerism
- must have C=C double bond
| - two different groups must be attached to EACH CARBON but one of the groups must be hydrogen
92
cis isomers?
hydrogen atoms on the same side of the molecule
93
trans isomers?
hydrogen atoms on different sides of the molecule (diagonal)
94
Cahn-Ingold-Prelog priority rule
priority is assigned to one of the groups on each carbon, two highest priority groups used to determine if E or Z.
- ATOMS directly attached to the double bond are assessed for priority by highest atomic number,
- if atomic numbers are the same then all atoms attached to that atom are listed from highest to lowest atomic number.
- compare the lists element by element and the list with the element with the highest atomic number is given priority
- double bonded atoms are counted twice in the list
95
types of addition reactions with alkenes
hydrogenation, halogenation, hydration
96
hydrogenation
hydrogen is added across the double bond, if enough hydrogen is present all of the double bonds are always broken. occurs with a nickel catalyst
97
hydrogenation of unsaturated fats forming trans double bonds
formed during the process of the pi bond breaking and reforming
98
unsaturated fats v saturated fats mpt
unsaturated fats have a lower mpt because they have a greater number of C=C bonds causing kinks in the chain so more difficult to pack together
99
hydrogenation of vegetable oils
naturally-occurring vegetable oils in the cis configuration so more difficult to pack together due to kinks in the chain. mpt increases when hydrogenated so solidify, some cis isomers become trans
100
halogenation
halogens added across a double bond, alkenes react with gaseous hydrogen halides to form haloalkanes
101
testing for alkenes/unsaturation
bromine water added across double bond, de-colourises if added across double bond so if bromine water decolourises then double bond(s) are present (the molecule is unsaturated)
102
hydration
alkenes react with steam to form alcohols in the presence of a phosporic acid catalyst or concentration sulfuric acid. the steam adds across the double bond, forming hydroxide groups to form an alcohol
103
why are alkenes more reactive than alkanes?
the pi bond is weaker than a sigma bond
104
what is electrophilic addition?
alkenes forming saturated compounds in addition reactions
105
why do electrophiles attack the double bond in alkenes?
has high electron density due to electrons in pi bond
106
definition of electrophiles
electron pair acceptors (usually a positive ion or slightly positive molecule)
107
key points to remember about drawing the reaction mechanisms in electrophilic addition
- curly arrows from the lone pair of electrons in the bond
- bond breaks by heterolytic fission in non alkene molecule (e.g. HBr)
- negative atom remaining = nucleophile
- electrophile (hydrogen) hydrolyses the double bond
- remaining carbon = carbocation (positive)
108
nucleophile
attacks the carbocation (have an electron pair so opposite of electrophile)
109
why are curly arrows used?
show movement of electrons, head of the arrow must point to where electrons will be when new bond formed
110
rate of reaction of electrophilic addition as you go down group 17
rate of reaction increases because atomic radius increases so strength of hydrogen-halide bond decreases. less energy required to break bond so rate of reaction increases
111
Markovnikoff's rule
determines the major product (most abundant) of the two isomers formed. when a hydrogen halide reacts with an unsymmetrical (not the same on both sides) alkene the hydrogen attaches to the carbon with the greatest number of hydrogens
112
types of carbocations in Markovnikoff's rule
primary, secondary, tertiary
113
primary carbocation
positive carbon only attached to one alkyl group (charge at end of chain)
114
secondary carbocation
positive carbon attached to two other alkyl groups
115
tertiary carbocation
positive carbon attached to three alkyl groups
116
why Markovnikoff's rule works
- most stable carbocations are more abundant as products
- secondary and tertiary carbocations are more stable because the positive charge can be decreased by the electrons on the alkyl groups.
- electron-donating/ electron pushing effect
- more alkyl groups = charge more spread out
117
electron-donating/ electron pushing effect
alkyl groups have an electron-donating/ electron pushing effect away from them (to the carbocation) due to the other end of the bond attracting the electrons more strongly,
therefore the movement of electrons towards the positive charge decreases the charge and the charge becomes more spread out
118
why are more stable carbocations more abundant as products?
less activation energy is required to form more stable carbocations so most of the mechanism occurs to form the most stable carbocations
119
definition for activation energy
the minimum energy needed before a reaction will occur
120
markscheme answer for explaining the most abundant carbocation formation
"The secondary (or tertiary) carbocation formed in this reaction is more energetically stable than the primary (or secondary) one which would be formed if the addition was the other way around, and so less activation energy is needed."
121
definition for polymerisation
an alkene (monomer) undergoing addition reactions with itself to form a polymer
122
conditions required for polymerisation
200°C, 200atm, a small amount of oxygen free radical as an initiator
123
definition for repeat unit
the specific arrangement of atoms in the polymer molecule that repeats over and over again
124
difference between addition polymers and copolymers
addition polymers = one type of monomer
| copolymers = two types of monomers in the same chain, alternating
125
key point about drawing polymerisation equations
ALWAYS DRAW EVERYTHING VERTICALLY
126
what type of bonds are between polymer chains?
london forces
127
how are alcohols bonded in polymers?
hydroxyl groups bond by hydrogen bonding due to slight dipoles on oxygen and hydrogen. bonding of two hydroxyl groups together is stronger than a hydroxyl group and a hydrogen
128
chain length determining properties of polymers
longer chains have stronger polymers as more london forces (more electrons)
129
side groups determining properties of polymers
polar side groups (e.g. hydroxyl) form stronger attraction between chains
130
branching determining properties of polymers
branching forms weaker polymers because can't pack together as well, unbranched polymers = more crystalline and stronger.
stretching plastic organises chains more closely so temporarily stronger before intermolecular bonds broken
131
cross-linking determining properties of polymers
increases mpt because chains more difficult to separate
132
high density poly(ethene)
linear chains, strong, high density
133
low density poly(ethene)
branched chains, weak, flexible, low density
134
uses of poly(ethene)
plastic supermarket bags, shampoo bottles, children's toys
135
PVC
poly(chloroethene) aka poly(vinyl chloride)
136
uses of PVC
gutters, records and windows
137
uses of tetrafluoroethene
non-stick pans, electrical/cable insulation
138
types of phenyl(ethene)
expanded, not expanded
139
other name for phenyl(ethene)
poly(styrene)
140
uses of expanded phenyl(ethene)
cups, packaging materials, thermal insulation
141
uses of not expanded phenyl(ethene)
toys, yoghurt pots
142
thermoplastics
no cross-linking, weak attraction between chains so low mpt, easy to mold when heating
143
thermosets
extensive cross-linking, strong attraction between chains so polymer keeps shape upon heating
144
methods of disposal of waste polymers
- recycling
- PVC recycling
- combustion for energy production
- feedstock recycling
145
recycling +/-
+ conserves finite fossil fuels
+ decreases waste to landfill
- discarded polymers must be sorted by type (unusable if mixed)
146
PVC recycling +/-
- high chlorine content and additives present so disposal and recycling hazardous
- releases HCl gas when burned (gas corrosive) and other pollutants (toxic dioxins) - can be removed from the waste gases by passing gas through alkali/carbonate
+ solvent reused
147
recycling
sorted, chopped into flakes, washed, dried, melted, cut into pellets, used by manufacturers
148
PVC recycling
solvents dissolve the polymer, PVC recovered from precipitation from solvent
149
combustion for energy production +/-
+high stored energy level
| -pollutants
150
why can some polymers only be used in combustion?
polymers derived from petroleum/natural gas are difficult to recycle
151
feedstock recycling +/-
+ able to handle unsorted and unwashed polymers
152
what is feedstock recycling?
chemical and thermal processes to reclaim monomers/gas/oils from waste polymers, products = raw materials
153
what are bioplastics?
produced from plant starch, cellulose, plant oils and protein. conserves oil reserves because not oil based
154
what can be used as a starting material in the production of bioplastics?
sugar cane
155
biodegradable polymers
- broken down by microorganisms into water, CO2 and biological compounds
- composed of starch or cellulose or contain additives to change polymer structure to be broken down by microorganisms
156
compostable polymers
degrade and leave no visible or toxic residues
157
alternative to alkene-based polymers
compostable polymers based on poly(lactic acid)
158
examples of using compostable polymers
- bags made from plant starch used as bin liners for food waste so bag and waste can be composted together
- plates, cups and food trays made from sugar cane fibres to replace expanded polystyrene
159
photodegradable polymers
a type of oil-based polymer used when plant-based alternatives aren't possible.
contain bonds weakened by absorbing UV light to start degradation. light-absorbing additives could be added
