Group 7

Question 1

Properties

Answer 1

1. diatomic
2. single covalent bond
3. form -1 ions

Question 2

Reactivity down the group

Answer 2

1. decreases
2. atomic radius increase
3. shielding increase
4. less readily reduced
5. worse oxidising agent

Question 3

Mpt and bpt down the group

Answer 3

1. increases
2. increased amount of electrons
3. increased dipole-dipole forces
4. more energy to overcome

Question 4

Displacement reaction

Answer 4

1. Cl2 displaces Br- and I-
2. Br2 displaces I-
3. I2 has no reaction
4. Br2 is yellow d

Question 5

Br2 in aqueous solution

Answer 5

yellow

Question 6

Br2 in hexane

Answer 6

orange

Question 7

I2 in aqueous solution

Answer 7

orange-brown

Question 8

I2 in hexane

Answer 8

violet

Question 9

Disproportionation

Answer 9

element is simultaneously reduced and oxidised

Question 10

Chlorine and water

Answer 10

Cl2(g) + H2O(l) ⇌ HCl(aq) + HClO(aq)

Question 11

Chlorate ionisation

Answer 11

HClO + H2O ⇌ClO- + H3O+

Question 12

Chlorate ions

Answer 12

ClO-
kills bacteria

Question 13

Chlorine and sodium hydroxide

Answer 13

2NaOH(aq) + Cl2(g) -> NaClO + NaCl + H2O

Question 14

Sodium chlorate(I)

Answer 14

1. NaClO
2. bleach
3. used in water treatment
4. bleaches paper and textiles

Question 15

Benefits of water treatment

Answer 15

1. kill disease-causing microorganisms
2. prevents growth of algae

Question 16

Disadvantages of water treatment

Answer 16

1. chlorine gas is toxic
2. chlorinated hydrocarbons are carcinogenic