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A-level Chemistry > 3.1.3 Group 7 > Flashcards

3.1.3 Group 7 Flashcards

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1
Q

volatility

A

how easily a substance turns from a liquid into a gas

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2
Q

what is the trend in volatility down the group 7

A

volatility decreases down the group

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3
Q

what is the trend in boiling points down the group 7

A

boiling points of the halogens increases down the group

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4
Q

why do boiling points increase down group 7

A

induced dipole dipole forces increase due to the molecules containing more electrons. Therefore, the induced dipole-dipole interactions require more energy to overcome.

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5
Q

what is the physical state of fluorine and chlorine

A

gas

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6
Q

what is the physical state of iodine and astatine

A

solid

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7
Q

what is the physical state of bromine

A

liquid

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8
Q

why would astatine be expected to react similarly to the other halogens

A

it is in the same group and so will have the same number of electrons in its outer shell

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9
Q

oxidation is the …….. of electrons

A

loss

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10
Q

reduction is the ……… of electrons

A

gain

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11
Q

the oxidising agent is …..

A

reduced

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12
Q

the reducing agent is …..

A

oxidised

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13
Q

what kind of agents do halogens act as

A

oxidising agents

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14
Q

displacement reactions

A

a reaction in which a more reactive element displaces a less reactive element from an aqueous solution of the latters ion

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15
Q

what colour is chlorine water

A

pale green

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16
Q

what colour is bromine water

A

orange

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17
Q

what colour is iodine water

A

brown

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18
Q

observations in chlorine water and bromide ions

A

pale green to orange

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19
Q

observations in chlorine water and iodide ions

A

pale green to brown

20
Q

observations of bromine water to chloride ions

A

no reaction, stays orange

21
Q

observations of bromine water to iodide ions

A

orange to brown solution

22
Q

observations of iodine water to chloride ions

A

no reaction, stays brown

23
Q

observations of iodine water to bromide ions

A

no reaction, stays brown

24
Q

which is the weakest oxidising agent

A

iodine

25
Q

which two oxidising agents are stronger than iodine

A

chlorine and bromine

26
Q

chlorine molecule

A

cl2

27
Q

chloride ion

A

cl-

28
Q

how can you confirm the identity of a halogen

A

add an organic solvent (cyclohexane) to the aqueous halogen and a more vivid colour will present

29
Q

what colour will cl2 be in cyclohexane

A

pale green

30
Q

what colour will br2 be in cyclohexane

A

orange

31
Q

what colour will I2 be in cyclohexane

A

purple

32
Q

disproportionation

A

when an element is being both oxidised and reduced in a redox reaction

33
Q

what are the conditions for disproportionation

A

cold dilute alkali

34
Q

what does a disproportionation reaction of cl2 produce

A

chloride ions and chlorate ions

35
Q

chlorate ions

A

ClO-

36
Q

what is formed is the disproportionation reaction between cl2 and water

A

HCL and HOCl (chloric acid)

37
Q

what kills bacteria and acts as a weak bleach

A

chlorate ion (OCL-)

38
Q

how can be identify the acidic nature of chlorine in water

A

blue litmus paper in aqueous chlorine will turn RED (acid) then COLOURLESS (bleach)

39
Q

why do people think we should not put chlorine inn drinking water

A

chlorine is toxic in excess

chlorine can react with hydrocarbons to form chlorinated hydrocarbons which are carinogens

40
Q

qualitative tests

A

rely upon simple observations rather than measurements

41
Q

what tests are carried out in order for an unknown inorganic compounds

A
  1. carbonate test
  2. sulphate test
  3. halide test
42
Q

what is formed when a carbonate reacts with acids

A

a salt, CO2, water

43
Q

how can we prove gas being formed is CO2

A

bubble through limewater which should turn cloudy with solid calcium carbonate forming

44
Q

why is the carbonate test always carried out first

A

there is no risk of an incorrect conclusion being made

45
Q

if you want to do a test for sulphate and a test for halides in the same test tube why do we need to use barium nitrate and not barium chloride

A

barium chloride would also supply a source of cl- ions, which would react with solve nitrate used in halide tests and a white precipitate will form giving a false positive for sulphate ions

A-level Chemistry (14 decks)

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