The Halogens

Question 1

what does F2 look like at rtp?

Answer 1

almost colourless gas

Question 2

what does Cl2 look like at rtp?

Answer 2

pale green gas

Question 3

what does Br2 look like at rtp?

Answer 3

red-brown liquid which easily vapourises giving brown vapour

Question 4

what does I2 look like at rtp?

Answer 4

grey-black solid which sublimes on heating giving purple vapour

Question 5

what’s the trend for colour down group 7?

Answer 5

colour gets darker

Question 6

what’s the trend for mp and bp down group 7?

Answer 6

increases, they get less volatile and switch from gas to liquid to solid (because intermolecular bonds get stronger)

Question 7

are halogens oxidising or reducing agents?

Answer 7

oxidising agents - have to gain one electron to achieve noble gas configuration

Question 8

how does oxidising power change up group 7 & why?

Answer 8

oxiding power increases up group 7 because as you go up the groups, the halogen has fewer shells so the incoming electron is closer to the +ve nucleus & less shielded so more strongly attracted

Question 9

why do 2 layers form when organic solvents and water are shaken?

Answer 9

organic solvents and water are immiscible (do not mix)

Question 10

what colour is Cl-?

Answer 10

colourless

Question 11

what colour is Br-?

Answer 11

colourless

Question 12

what colour is I-?

Answer 12

colourless

Question 13

what colour is Cl2 in aqueous solutions?

Answer 13

almost colourless

Question 14

what colour is Br2 in aqueous solutions?

Answer 14

orange

Question 15

what colour is I2 in aqueous solutions?

Answer 15

brown

Question 16

what colour is Cl2 in organic solvents?

Answer 16

pale green

Question 17

what colour is Br2 in organic solvents?

Answer 17

deeper orange

Question 18

what colour is I2 in organic solvents?

Answer 18

purple

Question 19

what happens when you mix a solution containing F- with AgNO3(aq)?

Answer 19

no ppt

Question 20

what happens when you mix a solution containing Cl- with AgNO3(aq)?

Answer 20

white ppt of AgCl

Question 21

what happens when you mix a solution containing Br- with AgNO3(aq)?

Answer 21

cream ppt of AgBr

Question 22

what happens when you mix a solution containing I- with AgNO3(aq)?

Answer 22

pale yellow ppt of AgI

Question 23

what happens when silver halides are left in sunlight?

Answer 23

they start to go grey/black due to the formation of silver

Question 24

what happens when silver halide ppts are shaken with aqueous ammonia solution?

Answer 24

AgCl: ppt dissolves, giving a colourless solution
AgBr: some ppt redissolves
AgI: ppt remains