Chemistry A2 Flashcards
(217 cards)
1
Q
In terms of B-L theory, what is an acid?
A
A proton donor
2
Q
In terms of B-L theory, what is a base?
A
A proton acceptor
3
Q
What holds ions together in a lattice?
A
Electrostatic attraction
4
Q
What kind of structure do metals have?
A
Giant metallic lattice structures
5
Q
Melting and boiling points of ionic lattices
A
High
6
Q
What is STP?
A
Standard temperature and pressure
7
Q
Typical state of ionic lattice at STP?
A
Solid
8
Q
Does solid ionic lattice conduct electricity?
A
No
9
Q
Does ionic liquid conduct electricity?
A
Yes
10
Q
Is ionic lattice soluble in water?
A
Yes
11
Q
Melting/boiling points of simple molecular?
A
Low
12
Q
Typical state of simple molecular at STP?
A
Sometimes solid, usually liquid or gas
13
Q
Does solid simple molecular conduct electricity?
A
No
14
Q
Does liquid simple molecular conduct electricity?
A
No
15
Q
Is simple molecule soluble in water?
A
Depends how polarised the molecule is
16
Q
Melting/boiling point giant molecular?
A
High
17
Q
Typical state of giant molecular at STP?
A
Solid
18
Q
Does giant molecular conduct electricity when solid?
A
No (expect graphit)
19
Q
Does giant molecular conduct electricity when liquid?
A
Generally sublimes so no
20
Q
Does giant molecular dissolve?
A
No
21
Q
Melting/boiling points of metallic?
A
High
22
Q
State of metallic at STP?
A
Solid
23
Q
Does solid metallic conduct electricity?
A
Yes
24
Q
Does liquid metallic conduct electricity?
A
Yes
25
Does metallic dissolve in water?
No
26
Do lone and bonding pairs repel the same?
No - lone pairs more
27
Shape of 2 electron pairs on central atom?
Linear molecules
28
Shape of 3 electron pairs on central atom?
Trigonal planar
29
Shape of 4 electron pairs on central atom?
Tetrahedral, trigonal pyramidal, bent
30
Shape of 5 electron pairs on central atom?
Trigonal bipyramidal
31
Shape of 6 electron pairs on central atom?
Octahedral
32
Bonding angle linear?
180*
33
Bonding angle trigonal planar?
120*
34
Bonding angle tetrahedral?
109*
35
Bonding angle trigonal pyramidal?
107*
36
Bonding angle trigonal bipyramidal?
90* and 120*
37
Bonding angle octahedral?
90*
38
What makes an alcohol primary/secondary/tertiary?
Primary - 1 C bonded to C OH is on
Secondary - 2 Cs bonded to C OH is on
Tertiary - 3 Cs bonded to C OH is on
39
Naming diols?
alkane-numbers-diol including e!!
40
Ether group?
-O-
41
Naming ethers?
alkOXYalkane (long then short)
42
Amine group?
NH2
43
Naming diamine?
[numbers]-diamino[alkane]
44
Ester group?
-COO-
45
Naming esters?
[alcohol]yl [alkane]oate
46
Aldehyde group?
-COH
47
Aldehyde naming?
[alkan]al
48
Ketone group?
R-CO-R'
49
Ketone naming?
[alkan]one
50
Mechanism of reaction Alkene -> Poly(alkene)?
Free radical polymerisation
51
Reagents/conditions Alkane -> Alkene?
Hydrogen gas, Nickel catalyst, 150*C, high pressure
or
Platinum catalyst, 20*C, high pressure
52
Reagents/conditions Alkene -> Bromoalkene?
HBr, 20*C
53
Reagents/conditions Alkene -> Dibromoalkene?
Br2, 20*C
54
Mechanism of alkene reactions?
Electrophilic addition
55
Reagents/conditions Alkene -> Alcohol?
Steam, 300*C, H3PO4 catalyst
or
Water, conc H2SO4 catalyst
56
Reagents/conditions Alcohol -> Alkene?
Al2O3 at 400*C
or
Reflux with conc. H2SO4
57
Type of reaction Alcohol -> Alkene?
Dehydration
58
Reagents/conditions Tertiary Alcohol -> Chloroalkane?
Shake with conc. HCl at room temp
59
Reagents/conditions Chloroalkane -> Amine?
Reflux with excess NH3 in ethanol solvent
60
Reagents/conditions Chloroalkane -> Alcohol?
Reflux with aqueous NaOH
61
Mechanism reaction Chloroalkane -> Alcohol?
Nucleophilic subsitution
62
Reagents/conditions Alcohol -> Ketone?
Reflux secondary alcohol with acidified potassium dichromate
63
Formula potassium dichromate?
K2Cr2O7
64
Reagents/conditions Alcohol -> Carboxylic Acid?
Reflux primary alcohol with acidified potassium dichromate
65
Reagents/conditions Alcohol -> Aldehyde?
Distill primary alcohol with acidified potassium dichromate
66
Reagents/conditions Aldehyde -> Carboxylic Acid?
Reflux with acidified potassium dichromate
67
Carboxylic Acid + Alkali -> ?
Salt + Water
68
Carboxylic Acid + Carbonate -> ?
Salt + Carbon Dioxide + Water
69
Alcohol + Carboxylic Acid -> ?
Ester
70
Reagents/conditions for Alcohol + Carboxylic Acid -> Ester?
Acid catalyst, usually conc. H2SO4
71
How do you test for phenol?
Shake with Iron(III) Chloride solution, turns purple
72
Phenol + Strong Base -> ?
Salt + Water
73
Acyl chloride group?
-COCl
74
Name acyl chloride?
[alkan]oyl chloride
75
Acyl Chloride + Phenol -> ?
Ester + HCl gas
76
HCN + Carbonyl compound -> ?
Cyanohydrin
77
What is a cyanohydrin?
A molecule with a CN and an OH group
78
Mechanism of cyanohydrin?
Nucleophilic addition reaction
79
What is a nucleophile?
Donates an electron pair to form a bond
80
What is an electrophile?
Accepts an electron pair to form a bond
81
Different types of reaction?
Rearrangement, addition, substitution, elimination, condensation
82
Different between elimination and condensation?
Elimination starts with 1 molecule, condensation with 2
83
What three questions do drug trials answer?
Is it safe?
Does it work?
Is it better than any current alternatives?
84
What energy does IR increase?
Vibrational
85
Two ways of making chromatography spots visible?
Plates with fluorescent dye added. Spots of chemical cover this, the rest glows under UV
Expose to iodine vapour, sticks to chemicals and shows up as purple spots
86
What is Rf value?
distance travelled by spot/distance travelled by solvent
Constant for each chemical so can be used to identify it
87
What can change Rf value?
Composition of TLC plate, the solvent, temperature
88
How can you work out the mass of a 'lost' mass spec fragment?
Difference between peaks
89
What is an amine?
Ammonia with one or more H atoms replaced by R group
One replace = primary
Two replaced = secondary
Three replaced = tertiary
90
Naming amines?
Amino[alkane]
91
Is an amine an acid, base or neither?
Base
92
Amine + Acid -> ?
Salt
93
What is an amide?
Contains group -CONH2
94
What is acylation?
Addition of an acyl group to a molecule [-C(-R)=O]
95
Amine + acyl chloride -> ?
N-substituted amine + HCL
96
What happens to the HCL formed as a byproduct of acylation of an amine?
Reacts with any remaining amine to for a salt
97
Products of hydrolysis of amides under acidic conditions?
Carboxylic acid and ammonium salt
98
Products of hydrolysis of amides under basic conditions?
Carboxylate ion and ammonia gas
99
Products of hydrolysis of ester under acidic conditions?
Acid and alcohol
100
Conditions for hydrolysis of ester under acidic conditions?
Reflux with dilute acid
101
Products of hydrolysis of ester under basic conditions?
Carboxylic acid salt and alcohol
102
Conditions for hydrolysis of ester under basic conditions?
Reflux with dilute alkali
103
How do you purify an organic solid?
Recrystallisation
104
How does recrystallisation take place?
1) Very hot solvent added to impure solid to the point it just dissolves
2) Gives saturated solution of impure product
3) Left to cool - forms crystals as it does
4) Impurities stay in solution
5) Crystals removed by filtration
105
What are the requirements of a solvent for recrystallisation?
Substance must be very soluble in hot solvent but nearly insoluble in cold solvent
106
What forms addition polymers?
Alkenes
107
What forms condensation polymers?
Two different types of monomer with at least two functional groups each that lose a water molecule for each bond formed
108
Product of dicarboxylic acids and diamines?
Polyamides
109
Product of dicarboxylic acids and diols?
Polyesters
110
What is an amide link?
-C(=O)-N-H-
111
What is an ester link?
-C(=O)-O-
112
Principles of green chemistry?
* Use reactants as safe and environmentally friendly as possible
* Use as few other materials, like solvents, as possible
* Use renewable raw materials where possible
* Keep energy use to minimum
* Generate no waste products hazardous to human health or environment
113
How does recycling and reusing polymers reduce CO2 emissions?
* Less energy required for high temp/pressure requirements of process therefore burns less fossil fuels
* Less landfill
114
Advantage of recycling plastics?
Reduce need for production of more
115
Disadvantage of recycling plastics?
Sorting and processing uses lots of energy
116
Advantage of burning plastics?
Reduces landfill
| Generates heat -> electricity
117
Disadvantage of burning plastics?
Produces CO2 and some toxic waste gases
118
Properties of longer chain plastics?
Stronger and less flexible because more intermolecular bonds between chains
119
What is Tm?
Melting point of a thermoplastic
120
What are thermoplastics?
Don't have any covalent bonds or cross links between molecules
121
What happens to a thermoplastic heated above Tm?
It will soften and then melt
122
What is Tg?
Glass transition temperature
123
What happens when a thermoplastic is cooled below Tg?
It will be brittle so snap or shatter
124
What are crystalline polymers?
Arrangement of chains is ordered
125
What are amorphous polymers?
Arrangement of chains is random
126
Which is stronger? Crystalline or amorphous polymers?
Crystalline because neatly ordered so closer together and stronger intermolecular forces
127
How do you modify a polymer to meet your needs?
Copolymerisation
Plasticiser
Cold-drawing
128
What is copolymerisation?
Making a polymer using a mixture of monomers
129
What is the use of a plasticiser?
Makes a polymer bendier by getting between chains and pushing them apart
130
What is cold-drawing?
Increases crystallinity of a polymer. Chains are pulled out in straight lines so chains lie closer together
131
Ways of measuring reaction rate?
* pH measurement
* Gas volume
* Loss of mass
* Colour change
* Titration
132
What does zeroth order with respect to a reactant mean?
If you double a reactant's concentration, the rate stays the same
133
What does first order with respect to a reactant mean?
Double the reactant's concentration, the rate also doubles
134
What does second order with respect to a reactant mean?
Double the reactant's concentration, the rate quadrouples
135
What is the rate equation?
=k[A]m[B]n
136
What is the overall order of a reaction?
Sum of each individual order
137
What is 'k' in the rate equation?
Rate constant: bigger = faster reaction
138
How is the rate constant affected by temperature?
Higher temperature = higher rate constant
139
How do you calculate initial rate?
Find the gradient of the tangent at time = 0
140
How can you determine order of reaction?
Experimentally by:
* Finding rate equation using initial rates
* Half lives from concentration-time graph
141
How do you determine order of reaction using half lives?
If the rate doesn't change it's zero order
If the rate changes and the half life value is constant it's first order
If the rate changes and the half life increases it's second order
142
What is the rate-determining step?
The step of a reaction with the slowest reaction rate
143
How do you know if a reactant is part of the rate determining step?
If it's in the rate equation, it affects rate so it or a derivative must be
If it's not in the rate equation, it can't be involved
144
What does the rate equation show about the number of molecules in the rate determining step?
The order of reaction shows the number of molecules of each type in the rate determining step
145
How can you predict the rate equation from the rate determining step?
If you know it, you know each reactant must be in it and the order will be the same as the number of molecules of each
146
What is happens to order in enzyme-catalysed reactions?
It changes as substrate is added, eventually becoming zero order as the reaction can go no faster
147
What are the steps on an enzyme catalysed reaction?
S + E -> ES
ES -> EP
EP -> E + P
148
Which is the rate determining step in an enzyme catalysed reaction?
Step 1 to start with, until no more enzyme is free to form ES complex. At this point, step 2 becomes rate determining
149
What does an amino acid contain?
Amino group, carboxyl group, H atom, variable group - all around central carbon atom
150
What is a zwitterion?
A dipolar ion - has both positive and negative charge in different parts
151
What is the isoelectric point of an amino acid?
The pH at which the average overall charge on the amino acid is zero - this is when zwitterions can exist
152
What happens when conditions are more acidic than isoelectric point?
NH2 group is likely to be protonated (N+)
153
What happens at the isoelectric point?
Zwitterion forms
NH2 is protonated (N+)
Carboxyl is negative (-O minus)
154
What happens what conditions are more basic than isoelectric point?
-COOH group likely loses a proton (-O minus)
155
How to identify amino acids in chromatography?
Spray with ninhydrin solution and they turn purple
156
How do proteins form?
Condensation polymers of amino acids
157
What is primary structure?
Sequence of amino acids in the polypeptide chain
158
What is the peptide bond?
CONH
159
What is secondary structure?
The shape of the chain - a-helix or b-pleated sheets
160
What is tertiary structure?
The 3D shape formed by extra bonding within the polypeptide chain
161
What holds secondary structure together?
Hydrogen bonds
162
What holds tertiary structure together?
* I-I dipole forces
* Ionic interactions between side groups
* Hydrogen bonding
* Disulfide bridges
163
What makes up a nucleotide?
Phosphate group, pentose sugar, base
164
How does the sugar-phosphate backbone form?
Condensation polymerisation
165
How does a base connect to its sugar?
Condensation reaction
166
How do enzymes improve green chemistry?
* Reduce temperatures
* Increase yields
* Less unreacted waste chemicals
167
What is a structural isomer?
Same molecular formula but atoms are arranged in a different way
168
What is a stereoisomer?
The orientation of atoms in space is different - E/Z and optical isomers
169
What is E/Z isomerism?
Isomerism due to no rotation around a double bond.
170
What are optical isomers?
Isomers that are mirror images of each other. Non-superimposable. Around a chiral carbon
171
What is a chiral carbon?
Has four different groups attached to it
172
Other name for optical isomers?
Enantiomers
173
What colour are manganate (vii) ions in aqueous potassium manganate (vii)?
Purple
174
What is a manganate(vii) ion?
MnO4-
175
What does a reducing agent do?
Donates some of its electrons to reduce something
176
What does an oxidising agent do?
Takes electrons away from something else to oxidise it
177
Oxidation state of uncombined chemicals?
0
178
Oxidation state of elements bonded to identical atoms? E.g. O2
0
179
Oxidation state of a simple monatomic ion? E.g. Na+
Same as its charge
180
Why must manganate ions be acidified to work as an oxidising agent?
So H+ ions can react with O2- ions when it is reduced
181
What kind of electrode do you use for different ions of the same element as a half cell?
Platinum or graphite - must conduct electricity and be inert so as not to react with the half cell contents
182
What is standard electrode potential?
The voltage of a half cell measured under standard when the half cell is connected to a standard hydrogen electrode
183
What are standard conditions for a half cell?
Solutions all 1moldm-3
Temp 25*C
Pressure 100kPa
184
Which metal is oxidised in an electrochemical cell?
The one with the most negative standard electrode potential
185
How do you calculate the cell potential?
E* more pos. - E* more neg
186
How do you know if a redox reaction is feasible?
If the standard electrode potential for what is being reduced is more positive, the reaction could take place
187
What are the steps of rusting?
1) 2H2O + O2 + 2Fe -> 2Fe2+ + 4OH-
2) Fe2+ + 2OH- -> Fe(OH)2
3) 2H2O + O2 + 4Fe(OH)2 -> 4Fe(OH)3
4) Gradually turns to hydrated iron(iii) oxide, Fe2O3.xH2O
188
What methods prevent rusting?
Barriers and sacrificial method
189
What barriers can prevent rusting?
Painting/coating with polymer
| Oiling/greasing
190
What is he sacrificial method of preventing rusting?
Place a more reactive metal over the iron. Water react with this instead of iron. Often Zinc.
191
What is galvanising?
Spraying zinc over an object
192
Process of iron recycling?
* Magnet used to separate iron from other stuff
* Melted in furnace, oxygen blown through to burn off impurities
* More iron and steel added to stop it getting too hot as burning off is exothermic
* Carbon and other elements added to obtain steel with exactly the desired properties
193
What is steel?
Alloy of iron and carbon
194
How are metals extracted from their ores?
Reduction by:
Heating with carbon
Reaction with more reactive metal
Electrolysis
195
How does reduction by heating with carbon work?
Carbon is oxidised, but doesn't work with reactive metals
196
How does reduction by reaction with a more reactive metal work?
Very reactive metals are powerful reducing agents
197
How does electrolysis work in extraction of metals?
Electric current passed through molten ore. Impurities collect below impure metal electrode, pure metal collects on negative electrode.
198
Which block are the transition elements?
D
199
What is a transition metal?
A metal that can form at least one stable ion with an incomplete d-subshell
200
Which elements fill subshells strangely?
Chromium and copper, both of which only fill up to 1 in 4s
201
What order are electrons lost in?
4s first
202
What are the properties of transition elements?
1) Can form complex ions
2) Can exist in variable oxidation states
3) Form coloured ions
4) Good catalysts because they can change oxidation states
203
What are complex ions?
Metal ions surrounded by ligands.
204
What is a ligand?
Any ion or molecule that forms a coordinate bond with a metal ion
205
What is a coordinate bond?
A dative covalent bond
206
What is the coordination number?
The number of coordinate bonds formed with the central metal ion (usually 4 or 6)
207
What is ligand substitution and what is a usual indicator?
Ligands exchanging places. There is normally a colour change.
208
Product and colour change of:
| [Fe(H2O)6]2+ + 2OH- -> ?
[Fe(H2O)4(OH)2] + 2H2O
| Green solution to green precipitate
209
Product and colour change of:
| [Fe(H2O)6]3+ + 3OH- -> ?
[Fe(H2O)3(OH)3] + 3H2O
| Orange/brown solution to rust-brown precipitate
210
Product and colour change of:
| [Cu(H2O)6]2+ + 2OH- -> ?
[Cu(H2O)4(OH)2] + 2H2O
| Pale blue solution to blue precipitate
211
Product and colour change of:
| [Cu(H2O)6]2+ + 2NH3 -> ?
[Cu(H2O)4(OH)2] + 2NH4+
| Pale blue solution to blue precipitate
212
Product and colour change of:
| [Cu(H20)6]2+ + 4NH3 -> ?
[Cu(NH3)4]2+ + 6H2O
| Pale blue solution to intense blue solution
213
What is a homogeneous catalyst?
In the same phase as the reactant chemicals
214
Why are transition metals good homogeneous catalysts?
They can easily be both oxidised and reduced, so can take electrons from one chemical and give them to another
215
What is a heterogenous catalyst?
In a different phase from the reactants
216
Why are transition metals good heterogenous catalysts?
They can use their s- and d- orbitals for bonding to the reactant molecules
217
Salters definition of enantiomer?
Isomers whose structures are mirror images and non superimposable
