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A Level Chemistry > past paper stuff > Flashcards

past paper stuff Flashcards

1
Q

how do London forces arise ???

A
  • uneven distribution of electrons
  • creates instantaneous (temporary) dipole
  • dipole is induced
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2
Q

what is the name given to repeating pattern of properties along a period ?

A

periodicity

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3
Q

what to remember with all calculations ?

A

does it ask for sig figs / decimal places ??

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4
Q

what does xH2O represent ?

A

water of crystallisation

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5
Q

what is a salt ?

A

metal /ammonium ion replaces H+ ion in an acid

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6
Q

define dative covalent bond

A

both electrons donated from same atom

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7
Q

define isotope

A

atoms of an element with same no of protons, diff no of neutrons

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8
Q

why do isotopes have similar chemical properties ?

A

same no. of electrons in outer shell

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9
Q

what to remember when drawing H bonds

A

lone pairs on Oxygen

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10
Q

what are conditions needed to make bleach ?

A

cold dilute NaOH

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11
Q

what is the 2nd product of metal + water/acid ?

A

hydrogen

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12
Q

what is meant by ionic lattice ?

A

repeating pattern of oppositely charged ions

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13
Q

pV =

A

nRT

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14
Q

what are the units of pressure in pV =

A

Pa

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15
Q

what are the units of volume in pV =

A

m3

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16
Q

what are the units of temp in pV =

A

kelvin

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17
Q

what is R in pV=

A

8.314 J / K / mol

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18
Q

what does roman numerals show

A

oxidation number

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19
Q

state two methods of carbon capture and storage

A
  • react with metal oxide to for metal carbonate

- deep in ocean

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20
Q

what are (2) factors of greenhouse effect of a gas ?

A
  • abundance

- ability to absorb IR

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21
Q

to be soluble in water, molecule must be able to …

A

form H-bonds with water

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22
Q

what is the oxidation of alcohols observation ?

A

orange to green

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23
Q

give two reasons why radical substitution produces a mixture of organic products

A
  • further substitution

- substitution at diff positions along chain

24
Q

give two reasons why enthalpy change of combustion isn’t very accurate

A
  • incomplete combustion may occur

- water / alcohol may evaporate

25
Q

when describe IR spectroscopy… what to remember

A
  • IR absorbance at …

- no absorbance at …

26
Q

what is a Brownsted-Lowry acid?

A

proton donor

27
Q

what observation for phenol + bromine ?

A
  • decolourises

- white ppt forms

28
Q

what gets oxidised and reduced in disproportionation ?

A

ELEMENT

29
Q

what are the conditions for formation of bleach ?

A

cold dilute (NaOH)

30
Q

suggest two reasons for why radical sub produces many products

A
  • further sub

- sub at diff positions on chain

31
Q

what are two factors of greenhouse effect of gas ?

A
  • conc

- ability to absorb IR

32
Q

state a biodegradable alternative for CFCs

A

hydrocarbon

33
Q

what is co solvent for testing for halides ?

A

warm ethanol

34
Q

What name is given to the process by which components in a mixture are
separated during gas/liquid chromatography?

A

Partition

35
Q

define average bond enthalpy

A

energy required to break 1 mol of bonds in gaseous molecules

36
Q

what to remember w/ rate constant ?

A

UNITS

37
Q

when forming mechanism for rate determining step thing, what must you not do ?

A

no intermediate electrons

38
Q

state two advantages of fuel cells compared w/ fossil fuel combustion

A
  • more efficient

- less CO2

39
Q

why is benzoic acid less reactive than benzene ?

A

COOH is electron withdrawing group, so decreases electron density

40
Q

how is conc of ozone maintained ?

A

O2 + O – O3
O3 – O2 + O
rate of O3 decomp = O3 formation

41
Q

state a disadvantage (apart from storage) of hydrogen fuel for fuel cell

A

hydrogen is explosive

42
Q

state a important difference between electrochemical and fuel cell

A

fuel cell requires constant fuel supply

43
Q

suggest why some people think use of hydrogen as fuel consumes more energy than fossil fuels

A

energy needed to make hydrogen

44
Q

what is the important factor when choosing suitable indicator ?

A

equivalence point matches pH range of indicator

45
Q

define relative atomic mass

A

weighted mean mass of an ATOM compared w/ 1/12th mass of carbon-12

46
Q

define electronegativity

A

ability of an atom to attract electrons in a covalent bond

47
Q

define covalent bond

A

strong electrostatic attraction between shared pair of electrons and nuclei of bonded atoms

48
Q

why is benzoic acid less reactive than benzene ?

A

-COOH is an electron withdrawing group so decreases electron density

49
Q

state 3 differences between Benzene and Kekule

A
  • hydrogenation of bonds less exothermic than expected
  • all bond lengths the same
  • requires high temp / halogen carrier (catalyst) for reaction
50
Q

state the difference of electrons between benzene and cyclohexene

A

cyclohexene - localised electrons

benzene - delocalised electrons (can’t polarise molecules)

51
Q

what is the HNMR standard ?

A

TMS

52
Q

why is benzene hydrogenation enthalpy less exo ?

A

benzene is more stable

53
Q

why are catalysts good ? (list)

A
  • can use reactions w/ less waste
  • less energy needed as no high temp
  • less fossil fuels used up
54
Q

how to get nitro group on phenol, directed to carbon 2 ?

A

low temp (lower than 50)

55
Q

state the reason for benzenes stability

A
  • delocalised rings above and below plane spread out negative charge
  • reluctant to undergo addition
56
Q

state conditions for alkene –> alcohol

A

steam, solid H3PO4 acid catalyst

57
Q

describe how to purify sample of X w/ separation

A
  • add sodium carbonate to remove acid catalyst
  • transfer to separating funnel and remove bottom layer
  • add drying agent (mag sulfate)
  • re distill at B.P. (or filter)

A Level Chemistry (21 decks)

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