1
Q
What is the shape of ammonia and an amide ion and what are the bond angles
A
Ammonia: trigonal pyramid 107°
Amide ion: bent 104.5°
2
Q
Amines are a group of nitrogen containing organic compounds that are derived from ammonia in which one or more of the hydrogen atoms in the ammonia molecule have been replaced by …… or ….. groups
A
Alkyl or Aryl groups
3
Q
How can you identify an amine
A
Amines have a distinctive unpleasant odour similar to a rotting fish smell
4
Q
Compare the boiling points of Amines to alcohols
A
They both form hydrogen bonds but hydrogen bonds in alcohol is stronger as O is more electronegative than N
Therefore boiling points of alcohols is higher than amines
5
Q
Why are phenylamines not very soluble in water
A
The benzene ring cannot form hydrogen bonds
6
Q
When naming an amine, how do you use the N in primary, secondary and tertiary amines
A
Primary amine: Don’t use N
Secondary amine: Use N only for the smallest group
Tertiary amine: Use N for each side group
7
Q
AMINE AS BASES
What does the strength of the base depend on
A
Base strength depends on the availability of the lone pairs on Nitrogen
8
Q
Explain how an amine having alkyl groups can affect its base strength
A
Alkyl groups push electrons away so greater electron density on the N atom
Lone pair on N atom is more available to accept H+ so stronger base
9
Q
Explain how an amine having a phenyl group can affect its base strength
A
Electrons delocalise into the ring so less electron density on the N atom. Lone pair on the N atom is less available to accept H+ so weaker base
10
Q
Order the following from weakest to strongest
Primary amines
Secondary amines
Tertiary amines
Ammonia
Aromatic amines
A
Aromatic amines
Ammonia
Primary amines
Tertiary amines
Secondary amines
11
Q
When you draw a repeating unit, do you include the brackets and the n
A
No
12
Q
How do you name a polymer
A
Poly(monomer)
Monomer is the one with the double bond
13
Q
AMINES AS BASES REACTING WITH ACIDS
- All amines will react with acids to become…(CH3NH2 + H+ -> ???)
- Are compounds soluble or not soluble (use phenylamine and phenylammonium chloride as an example)
- Addition of NaOH to an ammonium salt will form an…. (use CH3NH3Cl as an example)
A
- All amines will react with acids for become ammonium salts (CH3NH2 + H+ -> CH3NH3+)
- Compounds are soluble (phenylamine is not very soluble in water but phenylammonium amine is soluble)
- Addition of NaOH to an ammonium salt will solvent it back to the amine (CH3NH3Cl + NaOH -> CH3NH2 + NaCl + H2O)
14
Q
Basic buffers cab be made from combining a weak base with a salt of that weak base
What salts could be used to form buffers with these bases
Ammonia
Methylamine
Ethylamine
A
Ammonia and ammonium chloride
Methylamine and methylammmonium chloride
Ethylamine and ethylammonium chloride
15
Q
When nucleophillic substitution occurs to form aliphatic amines from halogenoalkanes, a mixture of Amines is formed and there is a lot of further substitutions
This produce a low yield of primary amines
How could you maximise the yield of primary amines
A
Add excess NH3
16
Q
When nucleophillic substitution occurs to form aliphatic amines from halogenoalkanes, a mixture of Amines is formed and there is a lot of further substitutions
How can you promote the formation of the quarternary salt
A
Add excess halogenoalkane
17
Q
Give a short flowchart of how halogenoalkans turn into quarternary ammonium salts via nucleophillic substitution
A
Halogenoalkane -> 1° amine -> 2° amine -> 3° amine -> Quartenary ammonium salt
18
Q
What is one use of quartnerary ammonium salts
A
Shampoo
19
Q
Preparation of 1° Amines using halogenoalkanes won’t produce a high yield bcs of further substitutions
What is a better method
Use CH3Br as the example and write down both equations
What does the second reaction require
What can this also be done by and how is it better
A
Convert a halogenolakane to a nitrile then reduce it to an amine
E.g. CH3Br + KCN -> CH3CN + KBr
CH3CN + 4[H] -> CH3CH2N2
LiAlH4 and ether
Reduction can also be done using catalytic hydorgenation (this is cheaper)
CH3CN + 2H2 -> CH3CH2NH2
Nickel
High pressure + High temperature
20
Q
When nitrocompounds are reduced into aromatic amines, what are the reagents and conditions required
A
Sn + HCl
Reflux
21
Q
In condensation polymerisation, what is inportant about each monomer
A
They should have the same functjonal group of both ends of the molecule e.g. diol, dicarboxylic acid, diamine, diacylchloride
22
Q
Condensation polymers are formed by reactions between what 3 pairs
A
Dicarboxyllic acids and diols
Dicarboxyllic acids and diamines
Amino acids
23
Q
When writing an equation for condensation polymerisation, why do you write (2n-1)H2O as the product
A
For every 2 monomer that join, one water molecule is released
24
Q
What is terylene an example of
What monomers is terylene made from
A
Polyester
Benzene-1,4-dicarboxyllic acid and ethane-1,2-diol
25
CONDENSATION POLYMERISATION
What does a Dicarboxylic acid and diol react to form
Polyster and water
26
CONDENSATION POLYMERISATION
What does a Dicarboxyllic acid and diamine react to form
Polyamide and water
27
What is Nylon 6,6 an example of and what is it made from
Polyamide
Hexane-1,6-diamine
Hexane-1,6-dicarboxylic acid
28
What is Kevlar made from
Benzene-1,4-dicarboxyllic acid and benzene-1,4-diamine
29
What are two examples of condensation polymers and what are sme common types of each
Polyesters(Terylene)
Polyamides(Nylon 6,6 and Kevlar)
30
Common substances used in everyday life often contain organic compounds
State what type of compound each of the following are and an everyday use
CH3(CH3)17COO-Na+
CH3(CH2)19COOCH3
[C16H33N(CH3)3]+Br-
CH3(CH3)17COO-Na+ (Carboxylate salt - Soap)
CH3(CH2)19COOCH3 (methyl ester - biodiesel)
[C16H33N(CH3)3]+Br- (quarternary salt - shampoo)
31
Polyesters and Polyamides can be broken down by ----- and therefore are ------
Is this a slow or quick process
Polyesters and Polyamides can be broken down by hydrolysis and therefore are biodegradable
Hydrolysis with water is very slow
32
In what conditions are polyamides hydrolysed more easily in
Acidic conditions (Amides Acidic)
33
In what conditions are polyesters hydrolysed more easily in
Basic conditions
34
What are some environmental advantages of rechargeable cells compared to non rechargeable cells
Less mining
Less waste
Less energy required to extract metals
35
Explain simply how a hydrogen oxygen fuel cell works
At the negative electrode, hydrogen reacts with hydroxide ions that have moved from right to left to lose electrons and form water. Through the osmotic effect, water diffuses to the right to the positive electrode. Oxygen reacts with water to gain electrons and forms hydroxide ions.
36
In the hydrogen oxygen fuel cell, what does the anion exchange membrane allow and not allow
It allows hydroxide ions but not O2 or H2
37
In the hydrogen oxygen fuel cell, what reacts to produce what at the negative electrode
Hydrogen and hydroxide ions react to release water and sme electrons
38
In the hydrogen oxygen fuel cell, what reacts to produce what at the positive electrode
Oxygen and water and electrons react to form hydroxide ions
39
What is the overall reaction in the hydrogen oxygen fuel cell
2H2 + O2 -> 2H2O
40
Suggest 2 reasons why the platinum electrodes are made from coating a porous ceramic material with platinum rather than using platinum rods
- Solid platinum rods are very expensive
- Increases surface area so faster rate of reaction
41
Explain why alkaline hydorgen oxygen fuel cells maintain constant voltage unlike ordinary cells
Fuel cells have a constant supply of hydrogen and oxygen
Concentrations of hydrogen and oxygen remains constant
42
Explain why a hydorgen fuel cell does not need to be recharged
It has a constant supply of hydrogen and oxygen
43
What is the issue with calling hydrogen oxygen fuel cells 'carbon neutral'
Hydorgen may need to be made using an energy source that is not 'carbon neutral'
44
What is the advantage of hydrogen oxygen fuel cells
The only product is water
Does not release pollutants like carbon dioxide, nitrogen oxides, sulfur dioxide, carbon monoxide or unburnt hydrocarbons
45
What is the main advantage of using hydorgen in a fuel cell rather than an internal combustion engine to provide energy
It is more efficient. It converts more of the available energy into kinetic energy.
46
What are two ways hydrogen can be produced by to use for hydrogen oxygen fuel cells and why is this not carbon neutral
Hydrogen can be produced by electrolysis or reacting methane with steam. The energy for both is released by burning fossil fuels with releases CO2
47
What are some disadvantages of using hydrogen oxygen fuel cells
- Hydrogen can be produced by electrolysis or reacting with steam. This energy is released by burning fossil fuels with releases CO2, so not very carbon neutral
- Hydrogen is highly flammable so problems with storing and transporting fuel
48
How is ethanol oxygen fuel cells more advantageous than hydrogen oxygen fuel cells
- Ethanol formed from fermentation is considered to be more carbon neutral and is made from a renewable source
- Raw material to produce ethanol by fermentation is abundant
- Ethanol is easier to store than hydrogen gas
49
Why are condensation polymers generally more stronger and more rigid than addifion polymers
- Condensation polymers has chains containing polar bonds and there are dipole forces and hydrogen bonding between chains
- Addition polymers only have VDW forces between the chains
50
Why do polyamides have a higher melting point that polyesters
- Polyesters have permanent dipole dipole forces between the C=O groups in the different chains in addition to the VDW forces between the chains
- Polyamides gave hydrogen bonding between the oxygen in C=O groups and the hydrogen in N-H groups in the different chains in addition to the van der waal forces
- Polyamides will therefore have higher melting points than polyesters as hydrogen bonding is stronger than dipole dipole forces
51
Are addition polymers biodegradable and why
They are not biodegradable as all bonds are non polar so its insoluble in water. It has strong VDW forces so is insoluble in non polar solvents. It is chemically inert
52
Are condensation polymers biodegradable and why
It is biodegradable as it has polar C-O and C-N bonds which CAN BE ATTACKED BY NUCLEOPHILES. Hydrolysis breaks them down very slowly into original monomers
53
What are 3 different methods of polymers disposal
Landfill
Incineration
Recycling
54
DISPOSAL OF POLYMERS
What are some advantages and disadvantages of landfill
ADVANTAGES
- Cheap and easy
- Condensation polymers are biodegradable
DISADVANTAGES
- Requires large areas of land
- Unsightly
- Waste decomposed, releasing CO2
55
DISPOSAL OF POLYMERS
What are some advantages and disadvantages of incineration
ADVANTAGES
- Heat produced can generate electricity
DISADVANTAGES
- Toxic gases and greenhouse gases released
56
DISPOSAL OF POLYMERS
What are some advantages and disadvantages of recycling
ADVANTAGES
- Less landfill/waste
- Cost is lower compared to making the plastics
DISADVANTAGES
- Polymers need collecting and sorting which is expensive in terms of energy and labour
- Polymers can only be recycled into the same type
- Plastic can be contaminated during the recycling process
57
What is the simple flow chart for recycling polymers
Collected -> Sorted -> Melted -> Reformed
58
What 4 groups do Amino acids have
Amine group
Carboxyl group
Hydrogen atoms
Variable group
59
All amino acids are chiral except ------ because -------
All amino acids are chiral except glycine because it has 2 hydrogen groups (instead of R it has H)
60
In Amino acids, which part tends to act as an acid and which part tends to act as a base
As it has both acidic and basic properties, what word can be used to describe it
Carboxyl group tends to act as an acid
Amine group tends to act as a base
Amino acids are amphoteric
61
Explain how Amino acids exist in strongly alkaline solutions and why
In strongly alkaline solutions, Amino acids exist as anions as the carbonyl group acts as an acid and loses H+ to form COO-
62
Explain how Amino acids exist in strongly acidic solutions and why
In strongly acidic solutions, Amino acids act has cations as the amine group acts as a base and accepts H+ to form NH3+
63
Since Amino acids have a Proton donating group and a Proton accepting group on the same molecule, each molecule can undergo an acid base reaction with itself to form a --------
Zwitter ion
64
What are dipeptides and what link are they joined by
Two amino acids with one amide link
65
When two different amino acids join, there are two possible combinations of the amino acids in the dipeptide. In what way does this happen
R and R' can be swapped
66
In living organisms, DNA lines up amino acids so these condensation reactions can occur to form the polymer....
Protein
67
HYRDOLYSIS OF PROTEINS
Proteins are ----- with --------- under ------- for 24 hours, forming individual amino acids
Why are the amino acids produced protonated
-Proteins are heated with concentrated HCL under reflux for 24 hours, forming individual amino acids
-Acidic conditions so amino acids are protonated
68
How can the composition of protein molecules be deduced
TLC (thin layer chromatography)
69
In TLC chromatography, Amino acids are transparent so how do you see the position of the spots
Spray the amino acids with ninhydrin and heat it to make it visible.
UV light can also be used to see the position of the spots
70
EXAM STYLE QUESTION on TLC
(a) Suggest a suitable reagent for the hydrolysis of a protein
(b) Suggest how the positions of the amino acids in the TLC plate were located
(c) Suggest why it was necessary to use two different solvents
(a) concentrated HCl
(b) use ninhydrin
(c) The amino acid doesnt dissolve in the first solvent, but dissolves in the second solvent
71
Dipeptides still have a -COOH and -NH2 groul so they can link further to form...
Polypeptides
72
Describe the primary structure of proteins
The sequence of 20 naturally occurring amino acids joined together by peptide links in a condensation reaction
73
In alpha helix, where are the R groups pointed
To the outside of the helix
74
What are the two types of secondary structures of proteins
Alpha helix
Beta pleated sheet
75
Describe the 3 different types of bonds in the tertiary structure of proteins
- Hydorgen bonds between amino acids
- Disulfide bonds between two amino acids if cysteine(The only amino acids with S)
- Ionic interactions between acidic amino acids and basic amino acids
76
Explain the origin of the interaction in alpha helix
- In N-H, N is more electronegative than H so N is delta negative and H is delta plus
- In C=O, O is more electronegative than C so C is delta positive and O is delta negative
- The lone pair of electrons on the O is attracted to the delta positive H on N
77
Enzymes are stereospecific meaning that...
They can only catalyse an individual enantiomer of a chiral molecule as they have a specifically shaped active site
78
79
What is the iupac name of all pentose sugars on DNA
2-deoxyribose
80
What is at the centre of a complex ion
Metal ion
81
What bond is present in all complex ions
Coordinate bond
82
Transition metals have the ability to form complex ions
Define a complex ion
A complex ion is a metal ion surrounded by coordinatley bonded ligands
83
What is a coordinate/dative bond[2 marks]
- It is a covalent bond
- Where both electrons are donated by one atom
84
A coordinate bond is formed when a transition metal ion reacts with a ligand
Explain how this coordinate bond is formed
Ligands have a pair of electrons so the ligand donates the electron pair to the metal ion
85
Define the term ligand
A molecule or an ion that donates a lone pair of electrons to a central metal ion to form coordinate bonds
86
There are three main types of ligands depending on the number of lone pairs they donate. These are...
Monodentate
Bidentate
Multidentate
87
Define the term coordination number
The number of coordinate bonds to the central metal ion
88
What is a monodentate ligand
Has one atom that can donate a pair of electrons to form 1 coordinate bond
89
What are 3 examples of monodentate ligands
H2O
NH3
Cl-
90
Give the name of two neutral monodentate ligands
Water and Ammonia
91
Give the name of one negatively charged monodentate ligand
Chloride
92
The oxygen atom in water had two lone pairs of electrons. Despite this water acts as a monodentate ligand. Explain why
The lone pairs of electrons are very close together
93
What is a bidentate ligand
Has two atoms that each donate a pair of electrons to form 2 coordinate bonds
94
What carboxyllic acid is ethanedioate derived from
Ethanedioic acid
95
What are two examples of bidentate ligands
Ethanedioate ion and Ethane-1,2-diamine
96
What is a multidentate ligand
Has several atoms, each donating a pair of electrons to form several coordinate bonds
97
What is an example of a multidentate ligand
There are 6 donor atoms, therefore it can be called more specifically a .....
EDTA⁴-
Hexadentate
98
What type of ligand is cyanide ion
Monodentate
99
[Cu(H2O)6]Cl2
Is the chlorine ion a ligand, explain why
No as Cu and (H2O)6 are coordinately bonded and [Cu(H2O)6]²+ and 2Cl- have ionic bonding
100
WATER
Type of ligand?
Formula?
Charge?
Monodentate
H2O
0
101
AMMONIA
Type of ligand?
Formula?
Charge?
Monodentate
NH3
0
102
CHLORIDE
Type of ligand?
Formula?
Charge?
Monodentate
Cl-
-1
103
ETHANE-1,2-DIAMINE
Type of ligand?
Formula?
Charge?
Bidentate
H2NCH2CH2NH2
0
104
ETHANEDIOATE ION
Type of ligand?
Formula?
Charge?
Bidentate
C2O4²-
-2
105
EDTA
Type of ligand?
Formula?
Charge?
Multidentate
EDTA⁴-
-4
106
What is the covalent bond between in DNA
The phosphate group of one nucleotide and the 2-deoxyribose of another nucleotide
107
Nucleotide join together to form polynucleotides. What type of bond is formed between two nucleotide
Covalent bond
108
Complex ions have different shapes. What two things does the shape of the complex depend on
Size of ligands attached
Coordination number
109
What is meant by similar size in monodentate ligands (H2O and NH3)
The atoms that donate electrons (O and N) are similar in size - they are both in period 2
110
Compared to H2O and NH3, why doesn't Cl- form an octahedral shape
Cl is in period 3 compared to O and N which are in period 2. Cl is larger than O and N so cannot fit as much ligands
111
Which one is bigger compared to the rest which are all similar in size
H2O
NH3
Cl-
C2O4²-
EDTA²-
Cl- is bigger
112
What are octahedral complexes surrounded by H2O ligands known as
Hexaaqua ions
Hexa - 6
Aqua- Water
Ion - Has an overall charge
113
Give examples of metal ions that can form octahedral complexes
Cu²+
Co²+
Fe³+
114
Give examples of metal ions that can form tetrahedral complexes
Cu²+
Co²+
Fe³+
115
Give examples of metal ions that can form square planar complexes
Pt²+
Ni²+
116
Give examples of metal ions thst can form linear complexes
Ag+
117
What is the coordination number and bond angle for octahedral complexes
Coordination number: 6
Bond angles: 90° and 180°
118
What is the coordination number and bond angle for tetrahedral complexes
Coordination number: 4
Bond angles: 109.5°
119
What is the coordination number and bond angle for square planar complexes
Coordination number: 4
Bond angles: 90°
120
What is the coordination number and bond angle for linear complexes
Coordination number: 2
Bond angles: 180°
121
Cancer is caused by cells in the body dividing and reproducing uncontrollably
What complex can be used as an anticancer drug
Cisplatin complex
122
Describe the structure of cisplatin
Pt²+ metal ion in the centre
Coordinately bonded to 2 NH3 and 2 Cl-
123
Compare the structure of cisplatin and transplatin
They both have Pt²+ metal ion in the centre
In cisplatin, the 2 NH3 are adjacent to eachother and 2 Cl- are adjacent to eacother, but in transplatin, the NH3 are opposite eachother and Cl- are opposite eachother
124
How does cisplatin prevent cell division of cancer cells
It binds to DNA, distorting its shape. The chlorine atoms in the cisplatin are displaced and a dative bond is formed between platinum and guanine in the DNA
125
What are some disadvantages of use of cisplatin as an anticancer drug
- Binds to DNA in healthy cells
- problem for healthy cells that replicate frequently (hair cells and blood cells)
- Causes hair loss and suppresses the immune system
126
How can side effects of cisplatin be reduced
- Low doses given to patients
- Targets tumour directly
127
Despite side effects, why is cisplatin still used
The ling term positives outweigh the negative short term effects
128
State how cisplatin affects cancer cells [2 marks]
Cisplatin binds to DNA causing its shape to distort. This prevents DNA replication
129
When referring to complexes, how do you name geometrical isomers instead of using E and Z
Cis and Trans
130
In an octahedral complex, how do you know if a molecule should be named cis or trans
Cis - 2 identical monodentate ligands 90° to eachother, next to eachother
Trans - 2 identical monodentate ligands 180° to eachother, opposite eachother
131
In order to have cis trans isometric in an octahedral complex, you must have
4 of one monodentate ligand
2 of another monodentate ligand
132
What isomerism does square planar complexes show
Cis trans isomerism
133
In order to have cis trans isomers in a square planar complex, you must have
2 of one ligand
2 of another ligand
134
What are the only types of complexes thst show optical isomers
Octahedral complexes
135
In order to have optical isomers in an octahedral complex you must have
3 bidentate ligands or 1 multidentate ligand
136
What is special about optical isomers in complexes
They have no plane of symmetry
137
What isomers can be formed from these shaped complexes
Linear
Square planar
Tetrahedral
Octahedral
Linear - none
Square planar - cis trans
Tetrahedral - none
Octahedral - cis trans and optical
138
What shape is cisplatin complexes
Square planar complexes
139
Via which reaction does cisplatin prevent dna replication
Ligand substitution reaction
140
Why is transplatin ineffective
It can't interfere with DNA in the same way as cisplatin
141
Give two examples of normal healthy cells that cisplatin prevents from reproducing
Blood cells
Hair cells
142
What are the 3 risks associated with cisplatin preventing normal healthy cells like blood cells and hair cells from reproducing
- suppresses the immune system increasing risk of infection
- Hair loss
- Kindney damage
143
What is the test and observation for acyl chlorides
Add water. If acyl chloride is presenting, white misty fumes of HCl is given off
144
What is the test for halogenoalkanes and observations
- Add aqueous sodium hydroxide to the sample and heat(a nucleophillic substitution reaction occurs and halide ions are produced)
- add nitric acid and silver nitrate
- A white ppt that is soluble in dilute ammonia indicates that a chloroalkane was present
- A cream ppt soluble in concentrated ammonia indicates a bromoalkane was present
- A yellow ppt insoluble in ammonia indicates a iodoalkane was present
145
What are the 3 main types of catalysts
Heterogeneous
Homogeneous
Autocatalysts (type of homogeneous)
146
What is a heterogeneous catalyst
The catalyst and reactants are in different physical states
147
What is a homogeneous catalyst
The catalyst and reactants are in the same physical states
148
What type of catalyst is an autocatalyst
What is an autocatalyst
A homogeneous catalyst
The catalyst is a reaction product
149
What are the 3 reactions where a heterogenous catalyst is used
Contact process - production of Sulfuric acid
Haber process - production of ammonia
Methanol production
150
What is the equation and catalyst for contact process - production of Sulfuric acid
What type of catalyst is this
SO2 + ½O2 -> SO3
V2O5
Heterogeneous catalyst
151
What is the equation and catalyst for haber process - production of ammonia
What type of catalyst is this
N2 + 3H2 <-> 2NH3
Fe
Heterogeneous catalyst
152
What is the equation and catalyst for methanol production
What type of catalyst is this
CO + 2H2 -> CH3OH
Cr2O3(chromium oxide)
Heterogeneous catalyst
153
CONTACT PROCESS - PRODUCTION OF SULFURIC ACID
SO2 + ½O2 -> SO3
What are the two steps in which the reaction proceeds
Explain why V2O5 is used in small pellets
SO2 + V2O5 -> SO3 + V2O4
V2O4 + ½O2 -> V2O5
It is used in small pellets to increase surface area
154
What are the 3 steps in the mechanism of a heterogenous catalyst
Adsorption
Reaction
Desorption
155
Explain the mechanisms behind a heterogeneous catalyst
Reactants are adsorbed on the active sites on the surface of catalyst.
Bonds in the reactant weaken and break and new bonds are formed by a reaction on the catalyst surface.
Products are desorbed from active site.
156
Why is silver a poor catalyst
Its adsorbtion is too weak to reactants are not brought together
157
Why is Tungsten a poor catalyst
Its adsorbtion is too strong so products are not desorbed
158
Explain why transition metals which adsorb strongly are not usually good catalysts
Products are not desorbed
159
Explain why transition metals which adsorb weakly are not usually good catalysts
Reactants are not brought together
160
Ni, Co, Fe, Ru, Rh, Pd and Pt are good catalysts because
Adsorption is the right strength
161
In what type of catalysts does catalytic poisoning occur in
Heterogeneous catalysts
162
How does catalyst poisoning occur and describe the effects
-Impurities are strongly adsorbed on the active site on the surface of catalysts
- This reduces the surface area of the catalyst and slows down the rate of reaction
- This reduces the amount of product that is formed in a certain time or with a certain amount of energy
- The catalyst eventually needs to be replaced which increases costs
163
Why is unleaded petrol used now when in the past, petrol contained lead
Lead poisoned the catalyst, reducing surface area for the reaction to take place
164
Sulfur poisons the ----- catalyst in the Haber process
Where does the sulfur come from
What is the equation for the reaction between iron and sulfur
Where does hydrogen come from for the Haber process
Sulfur poisons the iron catalyst
Sulfur comes from impurities in crude oil
Fe + S -> FeS
Hydrogen is obtained from electrolysis
165
In what two ways can you improve the efficiency of a heterogenous catalyst
Maximise the surface area
Remove catalyst poisons by ensuring the reaction mixture is pure
166
How does homogeneous catalysis work
Catalyst combines with one of the reactants forming an intermediate species.
The intermediate species then reacts with another reacfant forming the products and generating the original catalyst.
167
When looking at an energy profile diagram for a homogeneous catalyst, why are there two humps/bumps
There are 2 reactions
168
EQUATION FOR HOMOGENEOUS CATALYSIS
S2O8²- + 2I- ->
What are the catalysts required
What property allows it to act as a catalyst
S2O8²- + 2I- -> 2SO4²- + I2
Fe²+/Fe³+
Variable oxidation states
169
HOMOGENEOUS CATALYSIS
S2O8²- + 2I- -> 2SO4²- + I2
Explain using the equation above why the reaction will be slow without a catalyst present
Reactant ions are both negatively charged
Ions repel eachother and therefore are unlikely to collide and react
Activation energy of reaction is very high
170
HOMOGENEOUS CATALYSIS
S2O8²- + 2I- -> 2SO4²- + I2
Explain using the equation above why the addition of Fe²+/Fe³+ catalyst speeds up the rate of reaction
Reactant ion and catalyst ion are oppositely charged
Oppositely charged ions attract
Activation energy is lowered
171
What is the test for iodine
Add starch solution
If iodine is present, coour change to blue black
172
What is the test for iodine
Add starch solution
If iodine is present, coour change to blue black
173
What is the equation for Mn²+ autocatlaysing the reaction between MnO4- and C2O4²-
2MnO4- + 16H+ + 5C2O4²- -> 2Mn²+ + 8H2O + 10CO2
174
AUTOCATALYSIS
2MnO4- + 16H+ + 5C2O4²- -> 2Mn²+ + 8H2O + 10CO2
Explain using the equation above why the reaction will be slow without a catalyst present
Reactant ions are both negatively charged
Ions repel eachother therefore unlikely to collide and react
Activation energy of reaction is very high
175
AUTOCATALYSIS
2MnO4- + 16H+ + 5C2O4²- -> 2Mn²+ + 8H2O + 10CO2
Explain using the equation above why the formation of Mn²+ catalyst speeds up the rate of reaction
Reactant ion and catalyst ions are oppositely charged
Oppositely charged ions attract
Activation energy of reaction is lowered
176
AUTOCATALYSIS
2MnO4- + 16H+ + 5C2O4²- -> 2Mn²+ + 8H2O + 10CO2
State the role of H+ ions
Provides acidic conditions
177
Why do chemists try to find processes which do not require a solvent
Solvents can be expensive, difficult to dispose of and cannot be reused after a reaction has taken place
178
Why do chemists try and find processes which use non hazardous starting materials
Reactions are safer to operate and avoid having to dispose of any unreacted hazardous starting material
179
Give two ways a chemist can reduce the amount of waste produced in organic synthesis
Uses processed which have high percentage yield and high atom economy
180
When writing equations for an autocatalysis mechanism, what does MnO4- and C2O4²- turn into
What is the intermediate
Mn²+
CO2
Mn³+
181
When writing equations for an homoeogensis mechanism, what does S2O8²- and 2I turn into
What is the intermediate
SO4²-
I2
Fe³+
182
When forming an equation for the mechanism behind a catalyst, what must you ensure when combining key equations
The number of moles of the intermediate must be the same in both equations
183
In a redox reaction involving transition metals what is titrated against what
An oxidising agent is titrated against a reducing agent OR a reducing agent is titrated against an oxidising agent
184
Transition metals have variable oxidation states associated with -----
Colours
185
What is special about redox titration with transition metals
Therefore what is not needed
It is self indicating so no indicator needs to be added
186
What are the two pairs of reagents for redox titration with transition metals
MnO4- and Fe²+
MnO4- and C2O4²-
187
What is the point of infrared spectroscopy
Provides information about the functional geoups present in a compound
188
REDOX TITRATIONS
1. Which solution goes into the Burette usually
2. Which solution is measured using a pipette normally
3. Why dilute Sulfuric acid added in excess
4. What colour shows the end point
Oxidising agent
Reducing agent
Provides acidic conditions for the reaction
Pale pink
189
Why is a pipette used to measure the reducing agent and a burette to measure the oxidising agent
Pipette measured fixed volumes and burette measures variable volumes
190
Explain why concentrated oxidising agents must be kept away from flammable material
They provide excessive amounts of oxygen which can make substances combust easily
191
TRUE OR FALSE
Concentrated oxidising agents are flammable
FALSE They cause other substances to be flammable, not flammable itself
192
TRUE OR FALSE
A pipette us used because the volume of reducing agent must be accurate and fixed
TRUE
193
TRUE OR FALSE
A burette is used because the volume of oxidising agent needed is known in advance
FALSE
194
Why is dilute Sulfuric acid added rather than ethanoic acid in a redox titration reaction
Sulfuric acid is a strong acid but ethanoic acid is a weak acid
Sulfuric acid provides a higher concentration of H+ ions than ethanoic acid
195
Why is excess Sulfuric acid used in redox titrations
- To ensure the solution is acidic enough
- If excess is not used, MnO2 will form instead of Mn²+ and MnO2 is a brown coloured solid therefore difficult to see endpoint
196
REDOX TITRATIONS
Suggest one reason why the purple colour of manganate can be a source of errors when using a burette
Difficult to see the bottom of the meniscus
197
Why is hydrochloric acid not used in manganate reactions
HCl -> H+ + Cl-
2Cl- -> Cl2 + 2e-
Cl- ions would be Oxidised to Cl2 by MnO4-
This would lead to a greater volume of MnO4- being used and poisonous Cl2 being produced
198
REDOX TITRATIONS
Why is nitric acid not used in manganate titrations
Nitric acid is an oxidising agent
It Oxidises Fe²+ to Fe³+. This would lead to a smaller volume of MnO4- being used.
199
What are the two types of NMR
13C NMR - information about how the carbon atoms in a molecule are arranged
¹H NMR - information about how the hydrogen atoms in a molecule are arranged
200
How does NMR work
Any atomic nucleus with an odd number of nucleons in its nucleus has nuclear spin
This causes it to have a weak magnetic field
NMR spectroscopy looks at how this tiny magnetic field reacts when you put it in a larger external magnetic field
201
In H - NMR spectroscopy, what solvent is used
Any solvent without any 1H atoms so the solvent will not give any peaks
202
For C-13 NMR, there will be one peak present due to the solvent but why can this peak be ignored
It is known where this peak is
203
What is used to calibrate NMR spectrometer
A small amount of TMS (tetramethylsilane)
204
Why is TMS (tetramethylsilane) used for calibration of the NMR spectometer
- It only gives one absorption peak at delta = 0
- It is not toxic
- It is inert
- It is volatile - low boiling point so can be removed from sample easily
205
What is the structural formula of TMC
Tetramethylsilane
Si(CH3)4
206
What solvents can be used for NMR spectroscopy
CCl4. CDCl3
207
Compounds with a high oxidation state tend to be oxidising/reducing agent
Oxidising agents
208
Compounds with a low oxidation state tend to be oxidising/reducing agent
Reducing agents
209
A property of transition metals is their ability to exist in variable oxidation states. Changing oxidation states means what reaction is occurring
Redox reaction
210
Compounds with a high oxidation state tend to be oxidising/reducing agent
Oxidising agents
211
Compounds with a low oxidation state tend to be oxidising/reducing agent
Reducing agents
212
A property of transition metals is their ability to exist in variable oxidation states. Changing oxidation states means what reaction is occurring
Redox reaction
213
What 4 oxidation states can vanadium exist is
+5
+4
+3
+2
214
Vanadium exists in the following oxidation states: +5,+4,+3,+2
What is the formula and colour of each ion
+5. VO2+. Yellow
+4. VO²+. Blue
+3. V³+. Green
+2. V²+. Violet
You Better Get Vanadium
215
What colour is ammonium vanadate (V), but what colour is it often due to what
What is the formula
What is the oxidation state of Vanadium
In order to be reduced to the variable oxidation states, what must it be dissolved in
It is a white solid but is often yellow due to impurities
NH4VO3
+5
Sulfuric acid
216
Use an equation to show what happens to solid NH4VO3 when added to Sulfuric acid
NH4VO3 -> NH4+ + VO3-
217
Why is Sulfuric acid used to dissolve NH4VO3 rather than water
It is insoluble in water
218
What are the reagents in the reduction of Vanadium
Zinc and Sulfuric acid
219
REDUCTION OF VANADIUM
What 3 things are required
Name the gas produced when a metal reacts with an acid
Why is cotton wool used to stopper the flask rather than a bung
State and give two reasons why cotton wool is used to stopper the flask when V is reduced
- 3 required items: Zinc(reducing agent), Sulfuric acid, cotton wool
- Hydrogen gas
- Allows the hydrogen gas to escape to the surroundings so no pressure build up in flask
- Allows hydrogen gas to escape
- Prevents oxidation of vanadium by oxygen in the air because its difficult for oxygen to grt inside
220
What does redox potentials give an indication of
An atoms or ions ability to be oxidised or reduced
221
The more positive the redox potential, the ---- stable the ion will be and more likely to be ------- to a lower/higher oxidation state
The more positive the redox potential, the less stable the ion will be and more likely to be reduced to a lower oxidation state
222
Why are redox potentials of an ion not always the same as its standard electrode potential
It varies according to the environment the ion is in
223
What are 2 factors affecting redox potentials
pH and ligands
224
Explain how ligands affect redox potentials
Standard electrode potentials are measured in aqueous solution so any metal ion will be surrounded by water ligands. In a different environment the metal ion can be surrounded by different ligands. Different ligands will have stronger or weaker bonds to the metal ion. This affects the ability of the ion to gain or lose electrons and hence the redox potential. This means redox potentials can be larger or smaller.
225
Generally, redox potentials become more positive in more acidic conditions. Use the equation below to explain why
2VO2+ + 4H+ + 2e- <-> 2VO²+ + 2H2O
Adding more H+ shifts Equilibrium to the right to oppose to increase in [H+]. Increases the ions ability to accept the electrons which increases its ability to be reduced.
226
Why does Ag not show the following transition metal properties: Does not form coloured compounds, does not have variable oxidation states
Both the Ag atom and ion have a full d orbital
227
What do all silver complexes have an oxidation state of
+1
228
What transition metal properties does Ag show
- Forms complex ions e.g. [Ag(NH3)2]+ - Tollens reagent
- Can act as a catalyst however adsorption is too weak so reactant molecules are not brought together
229
What shape to silver complexes form
Linear
230
What is the oxidation state of silver in silver complexes
+1
231
What is the bond angle in silver complexes
180°
232
The silver ion has a large positive standard electrode potential so can easily be reduced to form ....
Silver
233
What is the molecular formula for Tollens reagent
[Ag(NH3)2]+
234
How is tollens reagent formed
Sodium hydroxide is added to silver nitrate solution. A light brown precipitate of Ag2O forms. Dilute ammonia solution is added to Ag2O until it redissolves. [Ag(NH3)2]+ is formed (this is colourless)
235
In a NMR spectometer, what does each peak represent
A environment
236
What does each peak on 1H NMR spectroscopy represent
A different proton environment
237
238
What rule does the splitting pattern in H NMR spectroscopy follow
n+1
239
In H NMR spectroscopy, when n is 0,1,2,3,4,5 what is the splitting type called
0 singlet
1 doublet
2 triplet
3 quartet
4 quintet
5 sextet
240
What can transition metal ions be identified by
Their colours
241
How are we able to see solutions in different colours
Wavelength of visible light is absorbed
d electrons excited to higher energy
Remaining wavelengths are reflected
242
When light is absorbed, what do d electrons move from and to
They need energy equal to what to do this
d electrons move from the ground state to an excited state when light is absorbed
They need energy equal to the energy gap, ◇E(This is the energy changes that occurs when a d electron in a transition metal ion is excited by visible lights)
243
Explain why electrons can be promoted in transition metals from the ground state to excited state
There is space for electrons to move
244
What is the equation for ◇E in transition metals
What does each symbol mean
What are the units
◇E = hv
◇E - energy absorbed by electron (J)
h - Planck's constant (Js)
v - frequency of light (Hz or s-¹)
Unit for ◇E = Js × s-¹ = J
245
FORMATION OF COLOURED IONS
What is the equation for speed of light
What does each symbol mean
What is the unit for wavelength
If wavelength is given in nm, what do you do
Speed of light = frequency × wavelength
c = v × lamda
Metres
×10-⁹
246
What are the 3 changes that can alter the size of ◇E between the d orbitals therefore leading to a change in colour
- Change in ligand
- Change in coordination number or shape
- Change in oxidation state of metal ion itself
247
Altering the size of ◇E alters the --------- required to promote the electron. As a different -------- is absorbed, the complimentary colours will be different so a different colour is observed
Altering the size of ◇E alters the FREQUENCY OF LIGHT required to promote the electron. As a different FREQUENCY is absorbed, the complimentary colours will be different so a different colour is observed
248
Sc³+ : [Ar]3d⁰
Why does this not form coloured ions
No d electrons to be excited
249
Zn²+ : [Ar]3d¹⁰
Why does this not form coloured ions
No vacant orbital into which electrons can be excited
250
What is the colour of Sc³+ in solution versus solid
Solution : Colourless
Solid : White
251
What can be used to determine the concentration of coloured ions in a solution
The more concentrated the solution -----
The less concentrated the solution -------
A simple colorimeter
The more concentrated the solution the more light absorbed
The less concentrated the solution the less light absorbed
252
What ions does bottled water contain
How is the concentration of the ion measured
What would the colorimeter reading be if carried out on the water sample, why
How will the bottled water industry determine a safe concentration of the ions in water then
Cu²+
Using a colorimeter
0, no light is absorbed, colorimeter can only be used if a solution is coloured
Add a colour enhancer e.g. NH3 or EDTA-⁴
253
What is an alternate method to colorimetery to measure concentration
Titration
254
What advantage does colorimetery have over titration when measuring Concentrations
Quicker to analyse
Only a small sample is needed
255
Does the size if the cuvette usined in colorimetery make a different to the results when measuring concentration
Yes ad absorption depends on path length travelled through solution
256
What is the role of the filter in colorimetery
The filter allows you to select the colour/frequency/wavelength that is most strongly absorbed by the solution
257
What are the 4 different possibilities of water ligand substitution
1. Water ligands relaced by other similar sized neutral ligands like NH3
2. Water ligands replaced by larger negatively charged ligands like Cl-
3. Water ligands can be replaced completely or partially
4. Water ligands can be replaced by bidentate or multidentate ligands - chelation
258
Which ions undergo substitution with similar sized ligand
If ligands are similar sized and both neutral, then the coordination number ------ and the oxidation state ------
For example: [Co(H2O)6]²+ + 6NH3 <-> [Co(NH3)6]²+ + 6H2
What is the colour of [Co(H2O)6]²+
What is the colour of [Co(NH3)6]²+
Cu²+ and Co²+
If ligands are similar sized and both neutral, then the coordination number remains the same and the oxidation state remains the same
Pink
Pale brown
259
Which ions undergo substitution with larger sized ligands
If ligands are larger in size and negatively charged then the coordination number ---- and the oxidation state ------
For example: [Cu(H2O)6]²+ + 4Cl- <-> [CuCl4]²- + 6H2O
What is the colour of [Cu(H2O)6]²+
What is the colour of [CuCl4]²-
Cu²+ and Co²+ and Fe³+
If ligands are larger in size and negatively charged then the coordination number changes and the oxidation state stays the same
Pale blue
Yellow green
260
Which ions undergo partial substitution with similar sized ligands
If ligands are similar sized and both neutral then the coordination number ----- and the oxidation state ------
For example: [Cu(H2O)6]²+ + 4NH3 <-> [Cu(NH3)4(H2O)2]²+ + 4H2O
What is the colour of [Cu(H2O)6]²+
What is the colour of [Cu(NH3)4(H2O)2]²+
Cu²
If ligands are similar sized and both neutral then the coordination number stays the same and the oxidation state stays the same
Pale blue
Deep blue
261
What are the conditions needed for ligand substitution where all ligands are removed
Excess reagent or concentrated reagent
262
What are the conditions needed for partial substitution in Cu²+ with mono/biodentate ligands (4 ligands in square plane removed)
Dilute reagent
263
ELONGATED OCTAHEDRAL COMPLEX
Explain why the H2O ligand coordinate bond is elongated above and below the square plane whereas the NH3 coordinate bonds are not
NH3 is a better ligand than H2O
Lone pair on N in NH3 is less strongly held than lone pair on O in H2O
Therefore, lone pair more readily donated to Cu²+ by N in NH3 than O in H2O
264
Why is the lone pair of electrons on Nitrogen in NH3 less strongly held than the lone pair of electrons on oxygen in H2O
Nitrogen is less electronegative than oxygen
265
Explaing the meaning of the term chelate effect
Substitution of a monodentate ligand with a biodentate or multidentate ligand
Forms a more stable complex
Leads to an increase in disorder
266
The stability of EDTA⁴- complexes have many applications. Name some
Added to river water to remove poisonous heavy metal ions
Added to shampoos to remove calcium ions present in hard water
Used in medicines
267
[Co(NH3)6]²+ + 3H2NCH2CH2NH2 <-> [Co(H2NCH2CH2NH2)3]²+ + 6NH3
Suggest why the value of the enthalpy change for this reaction is close to 0
6 Co - N bonds broken and then made
Template answer: Same number and same type of bonds broken and made
268
[Co(NH3)6]²+ + 3H2NCH2CH2NH2 <-> [Co(H2NCH2CH2NH2)3]²+ + 6NH3
Explain the thermodynamics reasons why this reaction occurs
Reaction goes from 4 moles of molecules to 7 moles of molecules
Disorder increases/Entropy increases
◇G is negative so reaction is feasible
269
[Co(NH3)6]²+ + 3H2NCH2CH2NH2 <-> [Co(H2NCH2CH2NH2)3]²+ + 6NH3
Explain why the complex ion formed as the product of the reaction above is more stable than [Co(NH3)6]²+
Reaction goes from 4 moles of molecules to 7 moles of molecules
Disorder increases/Entropy increases
◇G is negative so reaction is feasible
270
[Co(NH3)6]²+ + 3H2NCH2CH2NH2 <-> [Co(H2NCH2CH2NH2)3]²+ + 6NH3
Explain the thermodynamics reasons why this reaction occurs
Explain why the complex ion formed as the product of the reaction above is more stable than [Co(NH3)6]²+
What should this answer be based on and what keywords tell you this
THERMODYNAMIC REASONS and MORE STABLE tell you entropy should be the main part of the answer
271
What is the role of haemoglobin
Transport oxygen around the body
272
What is the central metal ion in haemoglobin
What is the coordination number
What is the shape
Fe²+
6
Octahedral
273
Explain the structure of the haemoglobin complex
- Contains an Fe²+ ions with a coordination number of 6 in an octahedral shape
- 4 positions are taken up by porphyrin ring in the square plane
- the protein globin is under the square planar
- Above the square planar is either H2O or O2
274
In the lungs the O2 concentration is high and therefore the water ligand is substituted for O2 to form...
Oxyhaemoglobin
275
O2 is carried by the complex and then substituted by H2O once delivered to required site which forms...
Deoxyhaemoglobin
276
Why is CO toxic (refer to haemoglobin)
CO forms a stronger coordinate bond than O2 and H2O to form carboxyhaemoglobin and displaces oxygen
Substitution cannot be undone as complex is more stable
277
Why is CO more strongly bonded to Fe²+ than O2 and H2O
Orientation of bonding and angle
278
When metal compounds dissolve in water, the water ligands form ------ bonds with the metal ion
This forms ------- complex ions
6 water molecules form 6 coordinate bonds with each metal in an -------- shape
Coordinate bonds
Metal aqua complex ions
Octahedral shape
279
ACIDIC NATURE OF METAL AQUA IONS
[M(H2O)6]²+ + H2O <->
[M(H2O)6]³+ + H2O <->
What reaction is this
This solution is weakly acidic as there is only slight dissociation
[M(H2O)6]²+ + H2O <-> [M(OH)(H2O)5]+ + H3O+
[M(H2O)6]³+ + H2O <-> [M(OH)(H2O)5]²+ + H3O+
This is a hydrolysis reaction
280
[M(H2O)6]²+ + H2O <-> [M(OH)(H2O)5]+ + H3O+
What is the role of [M(H2O)6]²+
What is the role of H2O
What is the pH of the resulting solution and why
Acid
Base
6.00 as H3O+ produced
281
[M(H2O)6]³+ + H2O <-> [M(OH)(H2O)5]²+ + H3O+
What is the role of [M(H2O)6]³+
What is the role of H2O
What is the pH of the resulting solution and why
Acid
Base
3.00 as H3O+ produced
282
On a metal aqua ion, what happened to acidity as the charge on the ion increases and why
Acidity increases
Electrin pairs are pulled away from the oxygen towards the metal ion
Electron pairs on the OH bond pulled even closer to oxygen than normal
Hydrogen atoms more positive than normal so can be pulled on in a reaction with water molecules
283
Which metal aqua complex, metal(II) or metal (III) has a higher pH at 1.00moldm-³ ? Explain your answer
M²+
M²+ has a smaller charge density that M³+
M²+ is less polarising than M³+
M²+ has less weakening effect in the OH bond than M³+
284
Hydroxide ions, ammonia and carbonate ions are all bases. These bases react with acidic metal aqua ions forming ------
Neutral precipitates
285
What are the 2 components that the mixture separating depends on
Solubility in solvent
Retention in the stationary phase
286
In chromatography, explain what it means by molecules are more attracted to 'like' molecules in terms of polarity
Polar molecules are more attracted to polar molecules
Non polar molecules are more attracted to non polar molecules
287
What are the 3 different types of chromatography
Column chromotography
Gas liquid chromotography
Thin layer chromotography
288
Explain what happens in column chromotography
A column is packed with a solid and a solvent moves down the column
The more soluble component passes through the column faster
The time for each component in the mixture to reach the end of the column is recorded (retention time)
289
Explain what happens during thin layer chromatography
A plate is coated with a solid and a solvent moves up the plate
290
In TLC why do you:
Wear plastic gloves
Put tiny drips using a capillary tube
Lid
Let it dry in a fume cupboard
To prevent contamination from hands to the plates
If drops are too big, different spots would merge
To prevent evaporation of solvent
Solvent is toxic
Chemistry
flashcards
Decks in class (22)
# Cards
-
Atomic Structure 3.1.140
-
Kinetics+Amount Of A Substance 3.1.2/559
-
Bonding 3.1.362
-
Chemical Equilibrium, Le Chatelier's Principle And Kc32
-
Introduction To Organic And Alkanes 3.3.1+283
-
Periodicity3
-
Group 2, The Alkaline Earth Metals 3.2.234
-
Oxidation, Reduction And Redox Equations19
-
Halogenoalkanes 3.3.329
-
Group 7, The Halogens 3.2.326
-
Alkenes 3.3.413
-
Energetics 3.1.421
-
Alcohols 3.3.540
-
Organic Analysis 3.3.613
-
Equilibrium Constant, Kp 3.1.1010
-
Rate Equations 3.1.932
-
Reactions Of Period 3 Oxides59
-
Thermodynamics77
-
Nomenclature And Optical Isomerism249
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Aromatic Chemistry22
-
Electrode Potentials63
-
Amines290
