Halogens [3]

Question 1

Halogen boiling point trend

Answer 1

The boiling point INCREASES as you go down a group. The heavier halogens have more electrons, leading to stronger temporary-induced dipoles (London forces) which take more energy to overcome.

Question 2

What colour is an aqueous chlorine solution?

Answer 2

Pale green

Question 3

What colour is an organic chlorine solution?

Answer 3

Colourless

Question 4

What colour is an aqueous Bromine solution?

Answer 4

Yellow

Question 5

What colour is an organic Bromine solution?

Answer 5

Orange

Question 6

What colour is an aqueous iodine solution?

Answer 6

Brown

Question 7

What colour is an organic iodine solution?

Answer 7

Purple

Question 8

What organic solvent should you use in a halide reactivity comparison experiment and why?

Answer 8

(Cyclo)hexane, to make any displacement clearer through colour changes

Question 9

Reactivity trend in halogens

Answer 9

Reactivity DECREASES down the group. This is because increases in shielding and atomic radius decreases the heavier halogen’s nuclear attraction to the valence electron. Therefore, it takes more energy to accept a valence electron and react.

Question 10

Define “disproportionation”

Answer 10

Disproportionation is when the same element in a reaction is both oxidised and reduced

Question 11

Water Sterilisation reactions

Answer 11

Cl₂(g) + H₂O(l) ⇌ HCl(aq) + HClO(aq)

Chlorine Gas + Water ⇌ Hydrochloric Acid + Chloric(I) Acid

Question 12

Chlorine + Sodium Hydroxide

Answer 12

Cl₂(g) + 2NaOH(aq) ➞ NaClO(aq) + NaCl(aq) + H₂O(l)