Question

Predict the outcome of the following reactions: (a) \(\mathrm{CuO}(s)+\mathrm{H}_{2}(g)\) (b) \(\mathrm{Na}_{2} \mathrm{O}(s)+\mathrm{H}_{2}(g)\)

Short answer

(a) Cu and water form; (b) no reaction occurs.

Step-by-step solution

Analyze Reaction (a) Type

Reaction (a) involves copper(II) oxide (CuO) and hydrogen gas (H₂). This is a redox reaction where a metal oxide is reduced by hydrogen gas, typically resulting in the formation of pure metal and water.

Write and Balance Equation for Reaction (a)

In (a), copper(II) oxide reacts with hydrogen gas: \[ \mathrm{CuO}(s) + \mathrm{H}_{2}(g) \rightarrow \mathrm{Cu}(s) + \mathrm{H}_{2} \mathrm{O}(l) \]This equation shows copper oxide being reduced to copper, with hydrogen being oxidized to water. The equation is already balanced.

Analyze Reaction (b) Type

Reaction (b) involves sodium oxide (Na₂O) and hydrogen gas (H₂). Typically, oxides of Group 1 elements like sodium do not easily undergo redox reactions with hydrogen gas. Sodium oxide can react with water instead.

Refute Apparent Reaction for (b)

The expected reaction, Na₂O with H₂ to form sodium and water, does not typically occur under normal conditions because sodium is much too reactive with water; thus, Na₂O is stable and does not easily react with hydrogen gas in this context. Thus, no reaction occurs in part (b).

Key concepts

copper(II) oxide reduction

In redox reactions, a substance is reduced while another is oxidized. When discussing the reduction of copper(II) oxide (CuO), we refer to the process where copper(II) oxide reacts with another substance, often resulting in the formation of elemental copper. In the specific reaction of copper(II) oxide with hydrogen gas, hydrogen acts as a reducing agent. It donates electrons to copper(II) oxide, resulting in the conversion of copper ions to copper metal. Thus, hydrogen gets oxidized to water. Generally, the reaction for copper(II) oxide reduction with hydrogen can be seen as follows:

• The Cu²⁺ in copper(II) oxide is reduced to Cu.
• H₂ is oxidized to H₂O.

This transformation underlines the importance of identifying oxidizing and reducing agents in any redox process.

metal oxides

Metal oxides are compounds composed of metal atoms bonded to oxygen. They are commonly found in nature and can have varied chemical properties. When discussing copper(II) oxide and sodium oxide, we encounter two different types of metal oxides. Copper(II) oxide is an oxide of a transition metal, while sodium oxide is an oxide of an alkali metal.

Metal oxides can be reduced to their respective metals under certain conditions, often involving a reducing agent like hydrogen. However, not all metal oxides react similarly. For example:

• Copper(II) oxide can be easily reduced by hydrogen because copper is a transition metal with a more complex electronic structure that allows for redox reactions.
• Sodium oxide does not easily undergo redox reactions with hydrogen because sodium is already in its most stable oxidation state, and its oxide does not favorably react with hydrogen under normal conditions.

chemical equation balancing

Balancing chemical equations is a fundamental skill in chemistry that ensures we account for the conservation of mass. This means that the number of atoms for each element must be the same on both sides of the equation. When we look at the reaction between copper(II) oxide and hydrogen gas, the unbalanced equation might initially look as follows:

• a \mathrm{CuO}(s) + b \mathrm{H}_{2}(g) \rightarrow c \mathrm{Cu}(s) + d \mathrm{H}_{2}O(l)

With a bit of analysis, we observe that each reactant and product must contain the same number of each type of atom. In this case, we find already balanced:

\[ \mathrm{CuO}(s) + \mathrm{H}_{2}(g) \rightarrow \mathrm{Cu}(s) + \mathrm{H}_{2}O(l) \]

• 1 copper, 1 oxygen, and 2 hydrogen atoms appear equally on both sides.

Achieving a balanced equation respects the law of conservation of matter, which is vital in predicting the outcomes of chemical reactions.

reaction analysis

Analyzing chemical reactions helps in understanding the underlying principles that govern chemical processes. In the context of these reactions, we distinguish between reactions that occur naturally and those that do not.

In reaction analysis, consider:

• Reactants and products: Identify what compounds are present at the start and what forms after the reaction.
• Change in oxidation states: This indicates which substance is oxidized and which is reduced.
• Feasibility: Assess conditions necessary for the reaction, such as energy or catalysts needed.

For example, the reaction between copper(II) oxide and hydrogen occurs naturally under normal conditions. Copper is reduced to its elemental state, and hydrogen is oxidized to water. In contrast, when analyzing the reaction between sodium oxide and hydrogen, it becomes evident that no reaction occurs without extraordinary conditions because sodium oxide is stable in regard to hydrogen. Sodium's high reactivity with water renders this reaction non-spontaneous under typical settings. Thus, understanding the nature of reactants and their potential interactions is crucial for predicting and explaining chemical reactions.