What are the common reactions of chlorine with metals?

Chlorine reacts with metals to form metal chlorides. For example, when chlorine gas reacts with sodium, it forms sodium chloride (NaCl). This reaction is highly exothermic and produces a bright yellow flame. Such reactions are typical for Group 17 elements, where chlorine acts as an oxidizing agent.

How does chlorine react with water, and what are the products?

When chlorine reacts with water, it forms a mixture of hydrochloric acid (HCl) and hypochlorous acid (HClO). The reaction can be represented as: Cl2 + H2O → HCl + HClO. This reaction is significant in water treatment processes, where chlorine is used to disinfect water.

What happens when chlorine reacts with hydrogen?

Chlorine reacts with hydrogen to form hydrogen chloride (HCl) gas. The reaction is highly exothermic and can be explosive in the presence of sunlight or a spark. The balanced chemical equation is: Cl2 + H2 → 2HCl. This reaction demonstrates chlorine's strong oxidizing properties.

Can chlorine react with organic compounds, and what are the implications?

Yes, chlorine can react with organic compounds in a process known as chlorination. For example, chlorine reacts with methane to form chloromethane and hydrogen chloride. This reaction is important in the production of various chlorinated organic compounds, which are used in industrial applications. However, chlorination can also lead to the formation of harmful by-products, such as chloroform, which is a concern in environmental chemistry.

Why is chlorine considered a strong oxidizing agent in chemical reactions?

Chlorine is considered a strong oxidizing agent because it readily accepts electrons from other substances during chemical reactions. This property is due to its high electronegativity and the ability to form stable chloride ions (Cl-). In reactions, chlorine can oxidize other elements, making it a crucial component in various industrial and laboratory processes.

Group 17(AS-Level Inorganic Chemistry)Cambridge International A Levels Chemistry (9701)

The reactions of chlorine

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Study Notes

Chlorine undergoes disproportionation reactions with both cold and hot aqueous sodium hydroxide, where it is simultaneously oxidized and reduced. Chlorine is also used in water purification due to its ability to kill bacteria and other microorganisms.

Disproportionation Reaction — a reaction where an element is simultaneously oxidized and reduced. Example: Chlorine reacts with sodium hydroxide to form chloride and chlorate ions.
Oxidation State — a number representing the total number of electrons an atom gains or loses. Example: In Cl2, chlorine has an oxidation state of 0, which changes in reactions with NaOH.
Hypochlorous Acid (HOCl) — a weak acid formed when chlorine reacts with water. Example: HOCl dissociates into H+ and OCl- ions, acting as a disinfectant.

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Key Definitions to Remember

Disproportionation Reaction
Oxidation State
Hypochlorous Acid (HOCl)

Common Confusions

Confusing the oxidation states of chlorine in different reactions
Misunderstanding the role of chlorine in water purification

Typical Exam Questions

What happens when chlorine reacts with cold aqueous sodium hydroxide? It forms NaCl, NaClO, and water through a disproportionation reaction.
How does chlorine purify water? Chlorine reacts with water to form HOCl, which kills bacteria.
What are the oxidation states of chlorine in its reaction with hot NaOH? Chlorine is reduced to -1 and oxidized to +5 and +7.

What Examiners Usually Test

Understanding of disproportionation reactions
Ability to identify changes in oxidation states
Knowledge of chlorine's role in water purification

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