3 - Uses of chlorine and chlorate(I)

Question 1

What is a disproportionation reaction?

Answer 1

A reaction where an element simultaneously oxidises and reduces

Question 2

What is the equation of the reaction between chlorine and water?

Answer 2

Cl_{2 (g)} + H₂O _(l) ⇌ HCl _(aq) + HClO _(aq)

Question 3

How do we know that Cl₂ underwent disproportionation in the reaction of chlorine and water?

Answer 3

The oxidation number of chlorine increases from 0 to +1 in HClO and decreases to -1 in HCl

Question 4

What are the benefits of using chlorine to treat water?

Answer 4

• Kills disease-causing microorganisms
• Prevents the growth of algae
• Removes bad tastes, smells and discolouration

Question 5

What are the risks of using chlorine to treat water?

Answer 5

• Chlorine gas causes severe irritation if inhaled
• Chlorine as a liquid can cause chemical burns
• Reacts with organics to form carcinogenic chlorinated hydrocarbons

Question 6

What is the equation of the reaction between chlorine and water in sunlight?

Answer 6

Cl_{2 (g)} + H₂O _(l) ⇌ 2HCl _(aq) + 1.5O_{2 (l)}

Question 7

Why is it a problem when chlorine reacts with water in sunlight?

Answer 7

The Cl₂ decomposes and does not undergo disproportionation so no ClO^- is produced

Question 8

What is the equation of the reaction between chlorine and dilute NaOH to produce the key components of bleach?

Answer 8

Cl_{2 (g)} + 2NaOH _(aq) → NaClO _(aq) + NaCl _(aq) + H₂O _(l)

Question 9

How do we know that Cl₂ underwent disproportionation in the reaction of chlorine and sodium hydroxide?

Answer 9

The oxidation number of chlorine increases from 0 to +1 in NaClO and decreases to -1 in NaCl

Question 10

Bleach solution contains chlorate(I) ions (ClO^-). How is this useful?

Answer 10

The chlorate (I) ions kill bacteria, making bleach widely useful for disinfecting and cleaning purposes