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AH Chemistry > past papers > Flashcards

past papers Flashcards

1
Q

what order do orbitals fill in according to the aufbau principle

A

1s 2s 2p 3s 3p 4s 3d 4p

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2
Q

how can you determine the shape of a molecule from its molecular formula

A

using that equation to work out how many electron pairs there are (bonding and non bonding)

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3
Q

how can you determine the conductivity of a solution when something has been added to water

A

look at the dissociation of ions because conductivity is just the movement of ions

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4
Q

does E have to be positive or negative for a reaction to be feasible

A

positive

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5
Q

why is ammonia a good nucleophile

A

has a lone pair and is attracted to centres of positive charge

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6
Q

what causes the separation of the ions in mass spectroscopy

A

a magnetic field

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7
Q

what is produced by reacting benzene with nitric or sulfuric acid

A

nitrobenzene

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8
Q

give an example of an aldehyde that would produce a primary alcohol

A

methanal

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9
Q

do ethers show hydrogen bonding

A

no

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10
Q

how do you work out the splitting pattern of a hydrogen atom in nmr

A

the number of peaks is equal to the number of adjacent hydrogen atoms - if it is attached to the same carbon it is not adjacent

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11
Q

when would volumetric analysis be more efficient than gravimetric analysis

A

when there are smaller quantities, as titrations are more suited to these

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12
Q

why would the optical activity of a substance decrease over time

A

because a racemic mixture is forming

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13
Q

suggest a suitable reagent for converting ketone carbonyl group to hydroxyl group

A

lithium aluminium hydride

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14
Q

what are the units for k in a zero order reaction

A

mol l-1 s-1

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15
Q

what are the units for k in a first order reaction

A

s-1

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16
Q

what are the units for k in a second order reaction

A

mol-1 l s-1

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17
Q

what are the units for k in a third order reaction

A

mol-2 l2 s-1

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18
Q

what is the value of l in an s orbital

A

0

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19
Q

what is the name given to chloride in a ligand if it is negative

A

chloro

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20
Q

what is the name given to cyanide in a negative ligand

A

cyano

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21
Q

what is the name given to hydroxide in a negative ligand

A

hydroxo

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22
Q

what is the name for ammonia when it is a ligand

A

ammine

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23
Q

what is the name for water as a ligand

A

aqua

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24
Q

what is the name for carbon monoxide in a ligand

A

carbonyl

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25
Q

what is the name for nitrate ion when it is in a ligand

A

nitrito

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26
Q

what is the name for the complex ion containing cobalt when there is an overall negative charge

A

cobaltate

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27
Q

what is the name for the complex ion containing iron when there is an overall negative charge

A

ferrate

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28
Q

what is the name for the complex ion containing copper when there is an overall negative charge

A

cuprate

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29
Q

if something has a low wavelength, its frequency is…

A

high

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30
Q

explain what is thought to take place when carbon atoms form four equivalent single bonds in methane

A

a combining of one s orbital and three p orbitals in what is known as sp3 hybridisation to form four degenerate hybrid orbitals

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31
Q

what is the reaction type of forming a haloalkane from an alcohol

A

substitution

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32
Q

give two reasons to explain why a reaction is more likely to take place via an Sn1 mechanism rather than an Sn2 mechanism

A

steric hinderance can prevent 5 numbered intermediate forming in the sn2 mechanism
the carbocation intermediate is stabilised by the inductive effect from the two alkyl groups in the intermediate

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33
Q

suggest why two isomers may be formed in an sn1 mechanism

A

the attacking group can attack from either side of the carbocation making both of the optical isomers

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34
Q

what is a reagent that could be used to form methyl benzene from benzene

A

bromomethane

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35
Q

what is a catalysis that could be used to form methyl benzene from benzene

A

aluminium chloride

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36
Q

why is benzene stable

A

the delocalisation of the electrons within the ring gives stability

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37
Q

which reagent could be used to carry out synthesis of an alcohol from an aldeyhde

A

lithium aluminium hydride

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38
Q

a solution of hypochlorous acid was titrated with sodium hydroxide solution. the solution at the end point was alkaline. explain fully why the solution was alkaline at the end point.

A

the hydrogen ions are removed by the conjugate base from the water equilibrium, and the equilibrium moves to the right.

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39
Q

suggest why the entropy change for liquid water to gaseous water is different to the same state change of carbon chloride

A

the entropy of liquid waer is much lower than that of carbon chloride and so there is more order - this is due to the hydrogen bonds.
the change from an ordered system of water to free molucules therefore results in a greater change in entropy than in carbon chloride

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40
Q

describe how separate samples of two enantiomer could be distinguished

A

their plane polarised light will be rotated in equal but opposite directions

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41
Q

state how sp2 hybridisation arises

A

one s orbital and two p orbitals combine to make three degenerate sp2 hybrid orbitals

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42
Q

why is it necessary to protect an amine group during synthesis

A

because the nitrogen of the amine group is a nucleophile and could also react

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43
Q

why is ethanol a suitable solvent for recrystallisation

A

the reactant is completely soluble in ethanol at high temperatures and only slightly soluble at low temperatures, which allows the formation of pure crystals when the solvent is cooled down.

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44
Q

state an effect on the impurities within a substance on the melting point

A

the melting point will have a wider range

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45
Q

why do impurities lead to a different melting point

A

there are weaker intermolecular forces in the pure substance compared to the impure one

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46
Q

what is the name of the reaction when an alcohol is converted to an ether

A

condensation

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47
Q

why can an integration curve be used to confirm if a sample is what it is meant to be

A

the ratio can agree with the ratio of hydrogen atoms in each environment

48
Q

what is meant by a monodentate ligand

A

a ligand that forms one dative covalent bond to a central metal ion

49
Q

explain the benefit of selling a drug with an equal mix of both enantiomers

A

it is cheaper to have a racemic mixture because you won’t have to separate the enantiomers

50
Q

describe how the technique of colorimetry can be used to determine the concentration of permangenate ions

A
  • several solutions of accurate concentration of the substance are made up
  • absorbance of each one is measured
  • calibration curve of concentration vs absorbance is drawn
  • the concentration of the solution with an unknown concentration of the substance can be determined from the calibration graph and its absorbance
51
Q

why is a reaction likely to continue

A

if the free energy is below zero and therefore remains feasible

52
Q

why are tertiary haloalkanes more suitable to use for nucleophilic substitution than primary or secondary

A

there is higher steric hindrance, so the carbocation is more stable

53
Q

how would you calculate the PH of an acid with a known concentration

A

using the formula that uses the literal concentration value

54
Q

why would a transition metal complex appear coloured

A

the ligand splits d orbitals, making them no longer degenerate.
energy corresponding to the wavelengths in the visible spectrum is absorbed, and this promotes electrons

55
Q

which type of bonds do sp3 hybridisation contain

A

only sigma

56
Q

how many sigma bonds are there between C-C

A

1

57
Q

how many pi bonds are there between C-C

A

0

58
Q

how many sigma bonds are there between C=C

A

1

59
Q

how many pi bonds are there between C=C

A

1

60
Q

how many sigma bonds are there between C-H

A

1

61
Q

how many pi bonds are there between C-H

A

0

62
Q

how many sigma bonds are there between N=C

A

1

63
Q

how many pi bonds are there between N=C

A

1

64
Q

how many sigma bonds are there between N-C

A

1

65
Q

how many pi bonds are there between N-C

A

0

66
Q

suggest a reason why bond angle is less in POCl3 than the bond angle in PCl4

A

there is stronger repulsion from the double bond

67
Q

what are tetradentate ligands

A

ligands that bind four donor atoms to a central atom to form a coordination complex

68
Q

why may something have a geometric isomer

A

restricted rotation due to double bond or ring structure

69
Q

how may a drug bind to the active site

A

the enzyme active site binds to parts of the molecule that have the ability to form hydrogen bonds

70
Q

do minor products have more or less stable carbocations

A

less stable carbocation.

71
Q

suggest a reagent for hydrolysing a nitrile into a carboxylic acid

A

any dilute acid, like hydrochloric acid

72
Q

what is the shape of a molecule with 2 bonding and 0 lone

A

linear

73
Q

what is the shape of a molecule with 3 bonding and 0 lone

A

trigonal planar

74
Q

what is the shape of a molecule with 4 bonding and 0 lone

A

tetrahedral

75
Q

what is the shape of a molecule with 2 bnding and 0 lone

A

non linear

76
Q

what is the shape of a molecule with 3 bonding and 1 lone

A

pyramidal

77
Q

what is the shape of a molecule with 5 bonding and 0 lone

A

trigonal bipyramidal

78
Q

what is the shape of a molecule with 6 bonding and 0 lone

A

octahedral

79
Q

what is the shape of a molecule with 4 bonding and 2 lone

A

square planar

80
Q

what happens to the value of entropy if a molecule because more ordered

A

it decreases

81
Q

how many pi bonds are there between carbon and nitrogen

A

2

82
Q

explain the effect of infrared radiation has on the bonds within molecules and how this allows different functional groups to be identified

A

the ir radiation makes the bonds in the molecule vibrate. different bonds in the functional groups absorb different wavelengths of light

83
Q

what do group 1 metals react with to form alkoxides

A

alcohols

84
Q

how do you order the ligands in the naming

A

alphabetically

85
Q

what is the prefix if there is only one ligand

A

mono

86
Q

what is the reaction name when reacting chloropropane with benzene

A

substitution apparently

87
Q

why would a back titration be necessary

A

because the substance is insoluble

88
Q

what are some analytical techniques that can be used to determine the concentration of metal ions in a compound

A

complexometric titration
absorption spectroscopy
precipitation

89
Q

how are nitriles formed

A

transition state

90
Q

which mechanism do primary haloalkanes react by

A

Sn2

91
Q

which mechanism do secondary haloalkanes react by

A

Sn2

92
Q

which mechanism do tertiary haloalkanes react by

A

Sn1

93
Q

why should the pH of a buffer solution remain constant when a small volume of water is added

A

because the acid and the salt are diluted by the same amount

94
Q

how could the alcohol and carboxylic acid be separated after hydrolysis of an ester

A

distillation

95
Q

what is the electrophile in a hydrogen halide

A

the positively charged hydrogen

96
Q

why is an aqueous solution of sodium benzoate alkaline

A

the ion from the salt removes hydrogen ions from the water (because its aqueous there is water)
this results in excess OH- ions from the water equilibrium

97
Q

do neon discharge lamps absorb radiation

A

no

98
Q

how do you determine if an indicator is suitable for determining the equivalence point

A

its pH range is within the vertical region on the graph

99
Q

what type of reaction is condensation

A

exothermic

100
Q

what type of reaction is neutralisation

A

exothermic

101
Q

which pH do amines have

A

an alkaline one

102
Q

what determines the type of structure adopted by a particular ionic compound

A

radius ratio of the ions

103
Q

what does the line on the graph for rate over concentration for a zero order reaction look like

A

a horizontal straight line

104
Q

what does the line on the graph for rate over concentration for a first order reaction look like

A

a straight line with a positive correlation as you increase the concentration

105
Q

what does the line on the graph for rate over concentration for a second order reaction look like

A

a curved line with a positive correlation as you increase the concentration

106
Q

what does the line on the graph for concentration over time look for a zero order reaction

A

a straiht line with a negative correlation as the time increases

107
Q

what does the line on the graph for concentration over time look like for a first order reaction

A

a curved line with a negative correlation that is quite a wide range of correlation

108
Q

what does the line on the graph for concentration over time look like for a second order reaction

A

a curved line with a negative correlation that has a much steeper correlation than in first order

109
Q

name the gas produced when water reacts with lithium aluminium hydride

A

hydrogen

110
Q

what should be added to a flask when heating under reflux

A

antibumping granules

111
Q

why are antibumping granules used

A

to prevent chemicals jumping up the reflux apparatus

112
Q

which technique could be used to both purify and identify a compound

A

distillation

113
Q

the absorption of radiation in the radiofrequency region causes proton nuclei to adopt a high energy state aligned against a strong magnetic field. explain how this leads to peaks in an nmr spectrum corresponding to different proton environments

A

the hydrogen nuclei flip to low energy and align with the magnetic field.
the different hydrogen environments have different energy gaps between high and low states

114
Q

what causes the splitting of d orbitals when a ligand binds

A

the repulsion from the lone pairs on the ligand

115
Q

what is meant by the term nucleophile

A

negatively charged ions that are electron rich

116
Q

why could two different drugs bind to the same receptor

A

they have the same structural fragment that binds to the receptor

AH Chemistry (35 decks)

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