mocks Flashcards
1
Q
Define ionisation energy
A
Energy required to remove one e- from each atom in 1 mole of gaseous atoms to form 1 mole of gaseous ions
2
Q
What factors affect ionisation energy
A
Shielding
Charge of nucleus
Distance from nucleus
3
Q
Ionisation energy pattern across periods
A
Increase
Distance from nucleus decreases and nuclear charge is increasing
4
Q
Ionisation energies pattern down groups
A
Decrease
More shielding and greater distance
5
Q
Four stages of TofF
A
Ionisation
Acceleration
Ion drift
Detection
6
Q
What is dative covalent/co-ordinate bonding
A
When both electrons in the shared pair of electrons come from the same atom
7
Q
Name and angle when co-ord no. is 2
A
180° Linear
8
Q
Name and angle when co-ord no. is 3
A
120° trigonal planar
9
Q
Name and angle when co-ord no. is 4
A
109.5° tetrahedral
10
Q
Name and angle when co-ord no. is 5
A
90° and 120° trigonal bipyradimal
11
Q
Name and angle when co-ord no. is 6
A
90° octahedral
12
Q
Why is bonding covalent instead of ionic?
A
Small difference in electronegativity
13
Q
Why is the m.p of aluminium higher than the m.p of sodium?
A
Al3+ has a greater charge than Na+ so there are more delocalised electrons and therefore a stronger attraction
14
Q
How does increases charge of nucleus affect IE?
A
increases IE
15
Q
How does increased distance from the nucleus affect IE?
A
decreased IE
16
Q
How does increased shielding affect IE?
A
decreases IE
17
Q
why do covalent macromolecular structures have high m.p?
A
lots of strong covalent bonds which require lots of energy to break
18
Q
why is graphite slippery?
A
weak vdw forces between layers so layers can slide easily
19
Q
why does graphite conduct electricity?
A
each carbon atom is bonded to 3 other carbon atoms so there are non-bonded delocalised electrons that can move through structure and conduct electricity
20
Q
why do molecular covalent molecules have a low m.p?
A
weak vdw forces between molecules so little energy required to overcome them
21
Q
name and shape of angle when there are 3 bonding pairs and 1 lone pair?
A
107.5 trigonal pyramid
22
Q
does a bigger molecule have stronger vdw forces?
A
yes - more electrons
23
Q
Difference between vdw and dipole-dipole forces?
A
vdw are temporary dipoles instead of permeant as there isn’t a big enough difference in electronegativity
24
Q
why does ice have a greater volume than water?
A
ice has more hydrogen bonds so is arranged in a regular lattice
25
why does ice float in water?
less dense as has a greater volume
26
enthalpy change defintion?
energy change of a reaction under constant pressure
27
standard enthalpy of combustion?
enthalpy change when one mole of a compound is completely burnt in oxygen with all the reactants and products in their standard states
28
standard enthalpy of formation?
enthalpy change when one mole of a substance is formed from its elements in their standard states and under standard conditions
29
enthalpy of atomisation?
enthalpy change when one mole of gaseous monatomic atoms are formed from their elements
30
first ionisation energy definition?
enthalpy change when one mole of gaseous atoms lose one mole of electrons to form one mole of unipositive cations
31
electron affinity definiton?
enthalpy change when one mole of gaseous atoms gains one mole of electrons to form one mole of uni negative anions
32
lattice enthalpy of disassociation?
enthalpy change when one mole of a solid ionic substance is disassociated into its consituent gaseous ions
33
lattice enthalpy of formation?
enthalpy change one mole of a solid ionic substance is formed from its constituent gaseous ions
34
enthalpy of hydration?
enthalpy change when one mole of isolated gaseous ions are hydrated with an infinitely large volume of water to form one mole of aqueous ions
35
enthalpy of solution?
enthalpy change when one mole of an ionic solid is dissolved in an infinitely large volume of water to form its constituent ions
36
why do we use a copper calorimeter?
good conductor of heat and has a low specific heat capacity
37
how do you calculate heat change (calorimetry)?
q = m c ΔT
38
reasons why value from calorimetry experiment might be less?
heat lost to surroundings
incomplete combustions
(faulty thermometer)
39
what is Hess's Law?
enthalpy change for a reaction is independent of the route taken
40
Le Chatelier's principle?
when a factor (e.g temp or pressure) is changed, an equilibrium will shift to oppose that change
41
what are the conditions of equilibria?
rate of forward and backward reactions are equal
conc. of reactants and products aren't changing
must be in a closed system
42
what happens when temp. decreases (eqm)?
exothermic direction is favoured, eqm shifts in that direction
means energy is released to the surroundings causing the temp. to increase
43
what happens when temp. increases (eqm)?
endothermic direction is favoured
energy is absorbed from the surroundings causing the temp. to decrease
44
what happens when pressure increases (eqm)?
eqm shifts to side with fewer moles to oppose change and decrease pressure
45
what happens when pressure decreases (eqm)?
eqm shifts to side with more molecules to oppose change and increase pressure
46
what is the Haber Process?
formation of ammonia (NH3)
N2 + 3 H2 ---> 2 NH3
<---
iron catalyst
47
ammonia?
NH3
48
ammonium?
NH4 +
49
theoretical conditions and actual conditions for max. yield of ammonia?
N2 + 3 H2 ---> 2 NH3
<---
(exothermic reaction)
theoretical:
high pressure
low temp
actual:
200 atm (expensive and engineeringly difficult)
450 c (faster rate)
compromised conditions
50
what affect does a catalyst have on the position of eqm?
it doesn't - increases both forward and backward reaction so will reach eqm faster
51
what is a redox reaction?
when reduction and oxidation occur simultaneously
52
what is oxidation?
loss of electrons
53
what is reduction?
gain of electrons
54
what is the exception for the oxidation state of H?
metal hydride e.g NaH
55
oxidising agent?
electron acceptor (it gets reduced)
56
reducing agent?
electron donor (it gets oxidised)
57
entropy defintion?
a measure of disorder
symbol = S
58
when is a reaction feasible? (ΔS)
when change in entropy is positive
ΔS > 0
59
how do you calculate ΔS?
ΣS products - ΣS reactants
60
Gibbs free energy equation?
ΔG = ΔH - TΔS
61
when is a reaction feasible? (ΔG)
ΔG < 0 - negative
62
at which electrode does oxidation occur?
left - negative terminal
63
at which electrode does reduction occur?
right - positive terminal
64
which electrode goes on the left?
the lowest EMF (smallest or most negative)
65
which half equation is reversed?
the more negative one
66
what is the purpose of the salt bridge?
its soaked in ionic solution (eg KNO3) and it completes the circuit to allow electrons to flow
67
what are the conditions of the standard hydrogen electrode?
298 K
100 kPa
conc. of all solutions 1moldm-3
68
how do you calculate EMF?
EMF RHS - EMF LHS
(bigger EMF - smaller EMF)
69
rules of conventional cell representation?
most oxidised species on the inside (closest to salt bridge)
more negative electrode potential on LHS (except H is always on left)
phase boundary whenever you change state
platinum on end if there's no solid
70
when and why do we use platinum in an electrochemical cell?
when there's no solid and because its unreactive and a good electrical conductor
71
properties of more negative EMF?
favours oxidation
best reducing agent
72
properties of more positive EMF?
favours reduction
best oxidising agent
73
when is a reaction feasible? (electrochemical cells)
EMF > 0
74
What are batteries?
types of electrochemical cells which convert chemical energy into electrical energy
75
where are lithium cells used and why?
mobiles because they’re rechargeable
76
example of what a lithium cell is made from?
lithium cobalt oxide electrode (LiCoO2)
graphite electrode
77
how do batteries recharge?
a current is supplied to force electrons to flow in the opposite direction and reverse the reactions
78
advantages of fuel cells?
more efficient
only waste product is H2O
don't need to be recharged
79
disadvantages of fuel cells?
need energy to produce a constant supply of hydrogen and oxygen which often comes from fossil fuels
hydrogen is highly flammable
80
example of hydrogen/oxygen fuel cell?
alkaline hydrogen - oxygen fuel cell used in vehicles
81
where are the chemicals stored in a fuel cell?
stored separately outside cell and fed in when electricity is required
82
what happens to the atomic radius across periods?
decreases because they have the same shielding but an increased no. of protons in the nucleus which means there is a stronger attraction
83
what happens to m.p across period 3?
(Na Mg Al Si P S Cl Ar)
from Na --> Al increases
(they are all metals so have high m.p due to metallic bonding but increase as nuclear charge increases)
increases to Si (highest m.p)
(macromolecular structure so has lots of strong covalent bonds)
P4 S8 Cl2
(all simple covalent structures but from lowest to highest m.p. Cl2, P4, S8 as more electrons means stronger vdw)
Ar is the lowest as monatomic so very weak vdw
84
what is the trend in reactivity down group 2?
reactivity increases as it becomes easier to oxidise atoms
85
group 2 reaction with water?
M + 2H2O ---> M(OH)2 + H2
86
magnesium reaction with steam?
Mg (s) + H2O (g) ---> MgO (s) + H2 (g)
87
what is the trend in solubility with OH- ions down group 2?
solubility increases down the group
88
what is the trend in solubility with (SO4) 2- ions down group 2?
solubility decreases down the group
89
use of Mg(OH)2 (s) ?
indigestion tablets
90
use of Ba(SO4) 2- (s) ?
barium meal (used in x-rays)
91
use of Ca(OH)2 ?
neutralising acidic soil
92
How do you test for (SO4) 2- , sulfate ions?
add dilute HCL and then BaCl2
positive result = white ppt (BaSO4)
93
test for CO3 2- ions (carbonate ions) ?
add dilute acid and bubble will be given off
94
test for Cl- ?
add dilute HNO3 and then dilute silver nitrate (AgNO3)
white ppt
95
test for Br- ?
add dilute HNO3 and then dilute silver nitrate (AgNO3)
cream ppt
96
test for I- ?
add dilute HNO3 and then dilute silver nitrate (AgNO3)
yellow ppt
97
flame test crimson red?
lithium
98
flame test yellow?
sodium
99
flame test lilac?
potassium
100
flame test blue/green?
copper
101
flame test brick red?
calcium
102
test for ammonium ions?
add warm dilute NaOH
gas given off turns damp red litmus paper blue
103
what happens when you add NH3 to AgCl, AgBr, AgI?
AgCl - dissolves in dilute
AgBr - dissolves in conc.
AgI - doesn't dissolve
104
which halide has the greater oxidising power?
Cl-
smallest atomic radius so strongest attraction to electrons
105
which halide has the greatest reducing power?
I-
biggest atomic radius so weakest attraction to electrons
106
what is a transition metal?
a metal that can form one or more stable ions and has a partially filled d-orbital
107
physical properties of transition metals?
high densities
high m.p
ionic radii are all very similar
108
chemical properties of transition metals?
can form complex ions
form coloured ions
good catalysts
exist in various oxidation states
109
what is a complex?
a complex has a central metal atom/ion surrounded by co-ordinately bonded ligands
110
what is a ligand?
an atom, ion or molecule that donates a pair of electrons to a central transiton metal ion to from a co-ordinate bond
111
example of a 6-coordinate bond and shape name complex?
[Fe(H2O)6] 2+
octahedral
112
example of a 4-coordinate bond and shape name complex?
[Cu Cl4] 2-
tetrahedral
113
example of a 2-coordinate bond and shape name complex?
[Ag (NH3)2 ] + Tollens Reagent
linear
114
what must ligands have to form a co-ord. bond?
at least one lone pair
115
what is a ligand that can form more than one co-ord. bond and give and example?
multi dentate
EDTA 4-
116
example of a bidentate ligand?
ethane - 1,2 - diamine
:NH2CH2CH2N:H2
117
what is haemoglobin made from?
Fe 2+ central metal ion (hexa- coord)
multidentate ligand which has four N co-ord. bonded to central atom
global which is a protein
and ten either a O2 or H2O which swaps so the complex can transport oxygen
118
what is a saturated hydrocarbon?
only has carbon carbon single bonds
119
what is crude oil?
a mixture of alkanes
120
why do bigger alkanes have higher m.p/b.p?
more atoms and electrons so greater vdw forces
121
what is cracking?
the decomposition of long carbon chain alkanes to make lots of more in demand smaller ones
122
what are the conditions for catalytic cracking?
450 c
catalyst - silica or alumina
123
what are the conditions for thermal cracking?
high temp - 1000C
high pressure
124
test for alkenes?
bromine water goes from orange to colourless
125
what is a use of alkenes?
used to make plastics
126
what compounds are typically made from catalytic cracking?
aromatic compounds and fuels (benzene ring)
127
what compounds are typically made from thermal cracking?
alkenes
128
what do we do with fuels?
combust them in oxygen
129
products of complete combustion?
CO2 and H2O
130
products of incomplete combustion (when there's not enough O2)?
CO (g) and H2O
131
products of incomplete combustion (there's very little O2)?
C (s) and H2O
132
what is the problem with sulphur dioxide?
forms acid rain which is a pollutant
133
how can you remove SO2 after a combustion recation?
react it with a base e.g CaO
134
what is the process of reacting SO2 with a base called?
flue-gas desulphurisation
135
where are nitrogen oxides formed?
combustion in car engines due to high heat and pressure
136
what are the three stages of free radical substitution?
initiation
propagation
termination
137
conditions for free radical substitution?
UV light
138
what do the dots in free radical substitution represent?
single unpaired electron
139
what are CFC's and what's the problem with them?
chloro-fluorocarbons
CFC's exist in our atmosphere due to aerosols and UV light from the sun causes their bonds to break which creates free radicals that then react with ozone depleting the ozone layer
140
what does the ozone layer do?
protects us from UV radiation
141
what type of reaction/mechanism occurs between halogens and alkanes?
free radical substitution
142
what is four in IUPAC (as in di, tri, ...., penta?
tetra
143
what is a nucleophile?
a molecule with a lone pair of electrons that has a tendency to donate the elctrons
144
what mechanism allows you to go from haloalkanes to alkenes?
elimination
145
what conditions and things do you need in elimination?
base/proton acceptor eg OH-
high temp
ethanol as a solvent
146
what is an alkene?
an unsaturated hydrocarbon
147
what isomerism do you get from C=C and why?
E-Z steroisomerism
restricted oration around the C=C
148
when is it Z?
together
149
when is it E?
apart (ew)
150
what is an electrophile?
electron pair acceptor
151
what is the organic reactant in electrophilic addition and why?
alkene - C=C is and electron dense area
152
what is the more stable carbonation and why?
the one with more alkyl groups attached as the alkyl groups push electrons onto the carbocation so spread the electrons around the molecule more evenly
153
what two methods can you use to make ethanol?
fermentation
hydration of ethene
154
conditions for fermentation?
yeast
oxygen free environment
temp 30-40 c
155
what are the advantages of fermentation?
sugars renewable
cheap equipment
156
what are the disadvantages of fermentation?
ethanol needs distilling
batch process - its not continuous
157
conditions for the hydration of ethene?
catalyst - conc. H2SO4
temp 300 c
pressure 70 atm
158
what are the advantages of the hydration of ethene?
produces a purer product than fermentation
continuous reaction
159
what are the disadvantages of hydration of ethene?
ethene is non-renewable
160
what do we use ethanol for?
biofuel so we combust it
161
what do you use to oxidise alcohols? (comparing primary, secondary and tertiary)
acidified potassium dichromate
K2Cr2O7
162
conditions when oxidising aldehyde?
heat under reflux
163
what do you get when you oxidise aldehydes?
carboxylic acids
164
what is the colour change when oxidising primary and secondary alcohols with K2Cr2O7?
orange to green
165
what does a primary alcohol turn into when you oxidise it?
aldehyde
166
what does a secondary alcohol turn into when you oxidise it?
ketone
167
what does a tertiary alcohol turn into when you oxidise it?
can't be oxidised
168
can an aldehyde be oxidised?
yes
169
can a ketone be oxidised?
no
170
can a ketone be oxidised?
no
171
test to distinguish aldehydes and ketones?
tollens reagent
aldehyde positive test (silver mirror) Ag+ ---> Ag
ketone NVC
fehlings solution
aldehyde positive test (blue solution to red ppt)
Cu 2+ ---> Cu +
ketone NVC
172
what is seteroisomerism?
same molecular and structural formula but different arrangements in space
173
what does chiral mean?
can't be superimposed
174
what does achiral mean?
can be superimposed
175
what is a racemic mixture?
a mixture which contains equal quantities of each enantiomer
176
What is the chelate effect?
Positive entropy change is always favourable as it means a more stable complex is being formed
177
What will be more acidic M2+ or M3+ and why?
M3+ as as it has a higher charge to size ratio so is more polarising so it pulls the electrons towards it which weakens the O-H bonds making it easier to lose a H+
178
What is cisplatin made from and what is it’s shape?
Central Pt ion/molecule
2 Cl ligands
2 NH3 ligands
Square planar
