3.1.3 Group 7

Question 1

volatility

Answer 1

how easily a substance turns from a liquid into a gas

Question 2

what is the trend in volatility down the group 7

Answer 2

volatility decreases down the group

Question 3

what is the trend in boiling points down the group 7

Answer 3

boiling points of the halogens increases down the group

Question 4

why do boiling points increase down group 7

Answer 4

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

Question 5

what is the physical state of fluorine and chlorine

Answer 5

gas

Question 6

what is the physical state of iodine and astatine

Answer 6

solid

Question 7

what is the physical state of bromine

Answer 7

liquid

Question 8

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

Answer 8

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

Question 9

oxidation is the …….. of electrons

Answer 9

loss

Question 10

reduction is the ……… of electrons

Answer 10

gain

Question 11

the oxidising agent is …..

Answer 11

reduced

Question 12

the reducing agent is …..

Answer 12

oxidised

Question 13

what kind of agents do halogens act as

Answer 13

oxidising agents

Question 14

displacement reactions

Answer 14

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

Question 15

what colour is chlorine water

Answer 15

pale green

Question 16

what colour is bromine water

Answer 16

orange

Question 17

what colour is iodine water

Answer 17

brown

Question 18

observations in chlorine water and bromide ions

Answer 18

pale green to orange

Question 19

observations in chlorine water and iodide ions

Answer 19

pale green to brown

Question 20

observations of bromine water to chloride ions

Answer 20

no reaction, stays orange

Question 21

observations of bromine water to iodide ions

Answer 21

orange to brown solution

Question 22

observations of iodine water to chloride ions

Answer 22

no reaction, stays brown

Question 23

observations of iodine water to bromide ions

Answer 23

no reaction, stays brown

Question 24

which is the weakest oxidising agent

Answer 24

iodine

Question 25

which two oxidising agents are stronger than iodine

Answer 25

chlorine and bromine

Question 26

chlorine molecule

Answer 26

cl2

Question 27

chloride ion

Answer 27

cl-

Question 28

how can you confirm the identity of a halogen

Answer 28

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

Question 29

what colour will cl2 be in cyclohexane

Answer 29

pale green

Question 30

what colour will br2 be in cyclohexane

Answer 30

orange

Question 31

what colour will I2 be in cyclohexane

Answer 31

purple

Question 32

disproportionation

Answer 32

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

Question 33

what are the conditions for disproportionation

Answer 33

cold dilute alkali

Question 34

what does a disproportionation reaction of cl2 produce

Answer 34

chloride ions and chlorate ions

Question 35

chlorate ions

Answer 35

ClO-

Question 36

what is formed is the disproportionation reaction between cl2 and water

Answer 36

HCL and HOCl (chloric acid)

Question 37

what kills bacteria and acts as a weak bleach

Answer 37

chlorate ion (OCL-)

Question 38

how can be identify the acidic nature of chlorine in water

Answer 38

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

Question 39

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

Answer 39

chlorine is toxic in excess | chlorine can react with hydrocarbons to form chlorinated hydrocarbons which are carinogens

Question 40

qualitative tests

Answer 40

rely upon simple observations rather than measurements

Question 41

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

Answer 41

1. carbonate test 2. sulphate test 3. halide test

Question 42

what is formed when a carbonate reacts with acids

Answer 42

a salt, CO2, water

Question 43

how can we prove gas being formed is CO2

Answer 43

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

Question 44

why is the carbonate test always carried out first

Answer 44

there is no risk of an incorrect conclusion being made

Question 45

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

Answer 45

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