Question

Give an example of hydrogen as (a) an oxidizing agent and \((b)\) a reducing agent.

Short answer

Hydrogen acts as an oxidizing agent in \( Mg + H_2 \rightarrow MgH_2 \) and a reducing agent in \( CuO + H_2 \rightarrow Cu + H_2O \).

Step-by-step solution

Understanding Oxidizing and Reducing Agents

An oxidizing agent is a substance that gains electrons during a chemical reaction, thereby oxidizing another substance. A reducing agent, on the other hand, gives away electrons to a substance, reducing it.

Example for Hydrogen as an Oxidizing Agent

To illustrate hydrogen acting as an oxidizing agent, consider the reaction between hydrogen gas (\( H_2 \)) and magnesium (\( Mg \)). In this reaction, hydrogen gains electrons from magnesium, which means it is reduced and thus acts as the oxidizing agent:\[ Mg + H_2 \rightarrow MgH_2 \]Here, \( H_2 \) is reduced to \( MgH_2 \).

Example for Hydrogen as a Reducing Agent

For hydrogen acting as a reducing agent, consider the reaction between copper(II) oxide (\( CuO \)) and hydrogen gas (\( H_2 \)). Here, hydrogen donates electrons to the copper oxide, reducing it to copper while itself being oxidized to water:\[ CuO + H_2 \rightarrow Cu + H_2O \]In this case, \( H_2 \) is oxidized to \( H_2O \) and acts as the reducing agent.

Key concepts

Hydrogen as Oxidizing Agent

Hydrogen can sometimes play the role of an oxidizing agent in chemical reactions. An oxidizing agent is a substance that accepts electrons from other substances. This means it causes another substance to lose electrons, which is known as oxidation.

In certain reactions, hydrogen accepts electrons, demonstrating its role as an oxidizing agent. Consider the interaction with magnesium. When hydrogen gas (\( H_2 \)) reacts with magnesium (\( Mg \)), the hydrogen molecules gain electrons. This reaction can be expressed as:

• \( Mg + H_2 \rightarrow MgH_2 \)

The magnesium atoms lose electrons while hydrogen atoms gain them, forming magnesium hydride. In this case, hydrogen acts as the oxidizing agent by accepting electrons and reducing itself.

Hydrogen as Reducing Agent

In many chemical reactions, hydrogen acts as a reducing agent. A reducing agent does the opposite of an oxidizing agent. It donates electrons to other substances, causing them to be reduced. This process also results in the oxidizing of hydrogen itself.

A classic example is the reaction between hydrogen gas (\( H_2 \)) and copper(II) oxide (\( CuO \)). In this reaction, hydrogen donates electrons to copper oxide, resulting in the formation of copper metal and water. This reaction is represented as:

• \( CuO + H_2 \rightarrow Cu + H_2O \)

Here, the hydrogen's electron donation reduces copper oxide to copper, while hydrogen is oxidized to water, showing its role as a reducing agent.

Chemical Reactions Involving Hydrogen

Hydrogen plays versatile roles in chemical reactions, often acting either as an oxidizing agent or a reducing agent, depending on the reaction partners. These reactions are crucial because they illustrate how hydrogen can change the oxidation state of other elements, which is fundamental in chemistry.

Understanding these interactions involves knowing:

• An oxidizing agent is reduced as it takes electrons.
• A reducing agent is oxidized as it donates electrons.

This behavior of hydrogen is exploited in various industrial and laboratory settings, including reactions that

• produce energy,
• refine metals,
• and manufacture key chemicals like ammonia.

Grasping these concepts helps us appreciate the significance of hydrogen in catalyzing important chemical processes.