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All AO1 Flashcards

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1
Q

Why is it necessary to ionise the isotopes of an atom before they can be analysed in a TOF mass spectometer

A

(Ions will interact with and) be accelerated (by an electric
field)
Ions create a current when hitting the detector OR
ions create a current in the detector/electron multiplier.

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2
Q

Isotope

A

Have same number of electron and proton but different number of neutrons.

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3
Q

Why isotopes of an atom have same chemical properties

A

Have same electronic configuration and chemical properties depend on the number of electrons in an atom

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4
Q

Relative atomic mass

A

Average mass of an atom of an element compared to 1/12 of mass of one atom in C12 isotope

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5
Q

Find the mass of ^53Cr

A

(53x10^-3)/6.02 x10^23

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6
Q

Why TMS is used as standard NMR

A

It generates on shears peak
Peak is always found in far right of spectrum
It is highly volatile this means can be removed from sample being tested after analysis fairly easily
Non reactive so won’t affect the sample being analysed

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7
Q

Resonance

A

The nuclei in lower energy state can absorb energy in form of radio waves and flip between the lower and higher levels
This is called resonance

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8
Q

C spectrum

A

No of peaks is same as no of carbon environment
Location of peaks tell u about the location of carbon environment

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9
Q

TMS

A

Reference of NMR spectrum
Tetra methylsilane

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10
Q

Why solutions with Fe3+ ions have lower pH than Fe2+ ions

A

Fe3+ ions have smaller atomic radius and a greater charge
Fe3+ ions can polarise water molecules easily
More O-H bonds can be broken so more H+ ions
More H+ ions more acidic the solution is and lower the pH is ,

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11
Q

Trend of atomic radius across period 3

A

Decreases because of increase in nuclear charge however sheilding remains same

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12
Q

Trend of electronegativity across P3

A

Inceases

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13
Q

Trend of 1st ionisation energy

A

increases along the period
same shielding effect and increase in nuclear charge

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14
Q

Why Al has lower IE than Mg

A

Mg has a 3s electron removed
Al has 3p electron removed
3p is higher energy than 3s

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15
Q

Why S has lower IE than P

A

P has a 3p electron removed which is unpaired
S has a 3p electron removed which is paired
S has a lower ionisation energy than P becuse of electron pair repulsion

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16
Q

Cl recation with water

A

Cl2 + H2O = HClO + HCl
this reaction is reversible

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17
Q

Cl + H2O =

A

HCl + O2

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18
Q

2Na + 1/2O2 =

A

Na2O

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19
Q

observation when Na reacts with oxygen

A

orange flame and white solid ppt

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20
Q

2Mg + O2 =
and observation?

A

2MgO
White flame
white solid ppt

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21
Q

4Al + 3O2 =
observation

A

2Al2O3
if you sprinkle aluminium powder you get bright white flames/ sparks
white solid

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22
Q

Si + O2
Observation

A

SiO2
Orange flame
white solid ppt

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23
Q

P4 + 5O2 =
Observation

A

P4O10
white flame
white fumes poduce (no ppt)

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24
Q

S + O2 =
observation

A

SO2
pale blue flame
no ppt ( colourless gas)

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25
Q

Trend of bonding across P3

A

ionic to basic

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26
Q

Why does Al2O3 have more covalent character than MgO

A

Al3+ ions are smaller in than Mg2+
This means the Al3+ ions is more polarising than Mg2+ ions
This distorts the electron cloud around the O2- ion more so that there is more electron density shared between two ions

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27
Q

Why sodium oxide form alkaline solution when reacts with water

A

Sodium oxide contains O2- ions
These O2- ions react with water to form OH- ions

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28
Q

Name insoluble oxides

A

Aluminium oxide and silicon dioxide

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29
Q

Relationship between bonding and acid/basic properties of P3 oxides

A

The oxides that are ionically bonded are alkaline
The oxides that are covalentalt bonded tend to be acidic

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30
Q

Amphoteric oxides

A

Al2O3
Can act as acid and a base

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31
Q

write an ionic equation for the reaction of phosphorus oxide with an excess of NaOH solution

A

P4O10 + 12OH- = 4PO4^3- + 6H2O

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32
Q

Explain using the equation why SiO2 is classified as an acidic oxide

A

SiO2 neuttralises bases
SiO2 + 2NaOH = Na2SiO3 + H2O

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33
Q

Dynamic equilibrium

A

The rate of forward reaction is same a rate of backward reaction
the amount of reactants and products is constant

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34
Q

Le chatalier principle

A

The equilibrium shift to oppose change

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35
Q

condition for equilibrium

A

closed system

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36
Q

Why does a catalyst not affect the position of equilibrium?

A

Catalysts increase the rate of the forward and backward reactions equally.

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37
Q

Why are catalysts added to the Haber process, which is a reversible reaction that produces ammonia?

A

To reduce the time taken to reach dynamic equilibrium

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38
Q

This question is about the equilibrium which occurs at temperature T1 between compounds as shown in the equation.

A(g)2B(g) ΔH = –50 kJ mol–1

The mixture was allowed to reach equilibrium at a different temperature T2, and the position of equilibrium had shifted to the right.

State and explain which of T1 or T2 is the lower temperature.

A

Forward reaction is exothermic
Equilibrium has shifted right to oppose the decrease in temperature
T2 is lower

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39
Q

Why are compromising conditions important in equilibrium

A

higher pressures would be too expensive
450oC gives a good yield in a fast time

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40
Q

Why is Kc used for?

A

Kc is a measure of how much the equilibrium has shifted to the right or left.

41
Q

How does an increase in pressure alter Kc? (1 Mark)

A

It remains unchanged

42
Q

State the features of homologous series.

A

Have same chemical properties
Have same functional group
Same general formula
Members show change in physical properties like boiling point increases as C chain gets longer

43
Q

Functional group isomers

A

Functional group changes but molecular formula is same

44
Q

To have E/Z isomerism a molecule must have

A

A double bond that restrict rotation
Each carbon has 2 different groups attached to it

45
Q

Alkane

A

alkanes are saturated hydrocarbons that contain Carbon-carbon and carbon-hydrogen single bonds only

46
Q

Why boiling point of alkanes increases as carbon chain length increases

A

More electrons so stronger vander waals

47
Q

Why increase in number of branches decreases boiling point

A

Less surface contact so weaker vander waals between chains

48
Q

what is fraction

A

Mixture of hydrocarbon with similar boiling points

49
Q

Explain why oil companies need to crack heavy fractions

A

Higher demand for more useful shorter chains (alkane and alkene)

50
Q

Thermal cracking gives

A

2 alkenes and 1 alkane

51
Q

Condition for thermal cracking

A

High temperature ( 700-1200 K)
High pressure (7000kPa)

52
Q

Catalytic cracking gives

A

High % of branched alakane and cycloalkane

53
Q

Condition for catalytic cracking

A

High temperature (700K)
catalyst = zeolite
mild pressure = 100kPa

54
Q

CO2, H2O are greenhouse gases and cause

A

Ozone depletion global warming

55
Q

why is incomplete combustion not desirable

A

produces
1 CO which is toxic ..binds to heamoglobin and reduces its oxygen carrying capacity
C particulate which can damage lungs and can make it difficult for asthma sufferers to breath

56
Q

SO2

A

Can cause acid rain
SO2 +1/2O2 +H2O = H2SO4
causes erosion of building , kill plants and aquatic animals

57
Q

Oxides of nitrogen

A

Nitrogen only reacts under high temperature
forms NO, NO2 and N2O4
N2 + O2 =2NO
NO + O2 = NO2

4NO2 + H2O + 1/2 O2 = 4HNO3

Nitogen oxides can bind with hydrocarbons and form photochemical fog

58
Q

Unburnt hydrocarbons can cause

A

cancer because they are toxic

59
Q

catalysts used in catalytic convertors

A

Pt and rhodium metal

60
Q

How can the amount of further substitution be reduced.

A

Add alkane in excess so halogen radical get used up by attacking alkane

61
Q

Why alkenes are ore reactive than alkanes

A

They are unsaturated so there is a scope to add atoms onto the molecule on either end of double bond to make it saturated

62
Q

Conditions for electrophillic addition with sulphuric acid

A

H2SO4 catalyst
70 atm pressure
high temperature (300-600 C)

63
Q

addition polymer

A

monomer = alkene
repeating unit = alkane

64
Q

plasticers

A

They are used to make polymers more flexible or less rigid

65
Q

Mechanical recycling for plastics

A

Plastics are sorted into different types
They are ground into pallet
Pallets are melted down and remould into new objects

66
Q

Feedstock recycling of plastics

A

Plastics are sorted into different types
They are then heated to break the polymer bonds
They are then repolymerised to make new plastics

67
Q

Why is reflux used to oxidise alchohol into carboxylic acid

A

It does not allow the reactants vapours to escape

68
Q

Test for H2 gas

A

Add a lit splint
A squeaky pop occurs

69
Q

Test for CO2

A

Bubble through lime water
Solution turns cloudy

70
Q

Test for O2

A

Add a glowy splint
The splint will re light

71
Q

What is low resolution mass spectrometery

A

Measure the Mr to 1 dp
Mr is same as m/z value

72
Q

Why high resolution spectrometry cannot measure the mr of propan-1-ol and propan-2-ol

A

Because they have same mr because they have same molecular formula

73
Q

Why does C has a relative molecular mass of 12

A

12C is standard reference

74
Q

Why can nucleophillic addition of aldehyde and ketones can form receamic mixture

A

The bonding about C double bond O is planer
This means 50 50 chance of nucleophile attacking on either side of molecule or other
This results in equal proportion of both optical isomer being made and so receamic mixture is formed
Receamic mixture is not optically active. The rotation of polarised light cancel out.

75
Q

Uses of quaternary ammonium salt

A

Hair conditioner and fabric softener
Also called catoinic sufacant

76
Q

How to ensure the higher yield of primary amine

A

Use large excess of ammonia

77
Q

What is the condition for further substitution in amines

A

Require excess haloalkane

78
Q

How is nitrile converted into amine

A

Reduction reaction
Requires H2 and nickle catalyst
CH3 CN + 2H2 = CH3CH2NH2

79
Q

Aycle chloride + water

A

Carboxylic acid

80
Q

Acyl chloride + alchohol

A

Ester

81
Q

Acyl chloride + ammonia

A

Amide

82
Q

Acyl chloride + amine

A

N substituted amide

83
Q

Why acid anhydrides are used more than Acyl chloride

A

Cheaper
Less corrosive
Don’t react with water
Less voilent so less exothermic

84
Q

What is the stationary phase in TLC

A

Silica gel

85
Q

how is a mixture seperated in chromatography?

A

Mixture is seperated either due to the difference in solubility in mobile phase or due to different affinities to stationary phase.

86
Q

Rf value

A

Distance moved by the component/ distance moved by solvent front

87
Q

Advantages of TLC

A

faster than paper chromatography
Will work on very small samples
Can be used to determine when a chemical reaction is complete

88
Q

Limitation of TLC

A

similar compounds may have similar Rf values
Condition must be kept same to fairly compare the Rf value
It can be difficult to find the solvent which separates all components of mixture
Cannot be used to separate large quantities

89
Q

Advantage of column chromatography

A

larger quantities can be separated

90
Q

What happens to the solubility of a polar compound if polar solvent is used in TLC?

A

solubility of compound increases and it travels further up the TLC plate

91
Q

What happens to the affinity of a polar compound if polar stationary phase is used in TLC?

A

Affinity increases and compound will not move very far

92
Q

column chromatography and polarity

A

If polar solvent is used,the polar molecule will dissolve well and will be collected at the bottom first and if a polar stationary phase is being used, the polar molecule will have a higher affinity and it will take longer for the polar compound to be collected at the bottom.

93
Q

Limitation of GC

A

Not all substances in the sample may ne separated and detected/peaks may be hidden behind others
Unknown compounds have no reference retention time

94
Q

GC-MS

A

GC can separate the components of the mixture but cannot identify them conclusively
MS cannot seperate the components in mixture but can identify them.

95
Q

USES of GC-MS

A

Forensics- minute particles at the scene of crime
can be identified, often providing evidence in court trial
Environmental analysis- Used to identify organic pollutants
Airport security- used to detect traces of explosive in luggage and on human
Space probes - spectometers have been sent to the Mars and Venus to collect and analyse materials and their environments

96
Q

Why data book do not usuall contain values of Ka for a strong acid

A

Strong acid dissociates completely
Ka value for strong acids tend to infinity/ very large/ cannot be divided by zero

97
Q

Explain how vander waals arise between between molecules

A

Electrons movement in first molecule forms a temporary dipole
This induces dipole in the other molecule
Attraction between opposite charges in adjacent molecules

98
Q

Identify the reagent or test that could distinguish between aqeous solution of SO2 or SO3 with same concentration

A

Reagent: pH meter
SO2 2-3
SO3 0-1
ORRR

Universal indicator
SO2 orange red
SO3 red

Chem (7 decks)

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