Elements from the Sea - Halogens

Question 2

What is the state and colour of Fluorine at rtp?

Answer 2

pale yellow gas

Question 3

What is the state and colour of Chlorine at rtp?

Answer 3

green gas

Question 4

What is the state and colour of Bromine at rtp?

Answer 4

red liquid, orange/red gas

Question 5

What is the state and colour of Iodine at rtp?

Answer 5

Grey solid, purple gas

Question 6

Which halogen reacts with water?

Answer 6

Fluorine

Question 7

What is the solubility of the halogens in water?

Answer 7

Cl, Br and I are not very soluble in water

F reacts with it - doesn’t dissolve at all

Question 8

What type of substance are the halogens very soluble in?

Answer 8

Organic solvents eg cyclohexane

Question 9

What colour is iodine when dissolved in water?

Answer 9

Brown/yellow

Question 10

What is the trend of electronegativity in the halogens?

Answer 10

Electronegativity decreases as you go down the group

Question 11

What is the trend of melting/boiling points in the halogens?

Answer 11

Higher mpt/bpt as you go down the group

Question 12

Why does the melting/boiling point increase down the halogens?

Answer 12

They have more electrons, so in an instantaneous dipole the intermolecular attraction is stronger

Question 13

Why do the halogens get less reactive down the group?

Answer 13

Distance between outer electron and nucleus is further

More energy needed to gain an extra electron

Lower electrostatic attraction / electronegativity

Question 14

What colour is chlorine when dissolved in water?

Answer 14

pale green

Question 15

What colour is bromine when dissolved in water?

Answer 15

orange/yellow

Question 16

What colour is iodine when dissolved in cyclohexane?

Answer 16

violet

Question 17

What colour is bromine when dissolved in cyclohexane?

Answer 17

orange/brown/red

Question 18

What colour is chlorine when dissolved in cyclohexane?

Answer 18

pale green

Question 19

How can the silver halides produced in the test for halogens be distinguished?

Answer 19

By adding ammonia solution:

Chlorine - colourless

Bromine - pale cloudy

Iodine - very cloudy

Question 20

What happens when potassium chloride is reacted with concentrated sulphuric acid?

Answer 20

white liquid formed that bubbles and fizzes to produce a white smoke

Question 21

What is produced when potassium chloride and sulphuric acid react?

Answer 21

HCl + KHSO₄

Question 22

What happens when potassium bromide reacts with sulphuric acid?

Answer 22

brown/orange liquid that evaporates into a white smoke

Question 23

What is produced when KBr reacts with H₂SO₄ ?

Answer 23

SO₂ + Br₂ + H₂O

Question 24

What happens when potassium iodide reacts with sulphuric acid?

Answer 24

brown/grey liquid produced that fizzes and bubbles

Question 25

What is produced when KI reacts with H₂SO₄?

Answer 25

hydrogen sulphide, iodine and water

Question 26

Which halogen is the strongest oxidising agent?

Answer 26

Fluorine

Question 27

Which halogen is the strongest reducing agent?

Answer 27

I^-

Question 28

What is produced when hydrogen halides react with sulfuric acid?

Answer 28

Fluoride and Chloride - don't react Bromide - produces sulfur dioxide Iodide - produces hydrogen sulfide

Question 29

What happens when the hydrogen halides react with ammonia?

Answer 29

a white cloud of ammonium halide is produced

Question 30

Which hydrogen halides can be thermally decomposed?

Answer 30

hydrogen bromide hydrogen iodide