Question

Write a balanced net ionic equation for the reaction of each of the following oxides with water: (a) \(\mathrm{BaO}\) (b) \(\mathrm{Cs}_{2} \mathrm{O}\) (c) \(\mathrm{N}_{2} \mathrm{O}_{5}\)

Short answer

(a) \(\text{BaO} + \text{H}_2\text{O} \rightarrow \text{Ba}^{2+} + 2\text{OH}^-\); (b) \(\text{Cs}_2\text{O} + \text{H}_2\text{O} \rightarrow 2\text{Cs}^+ + 2\text{OH}^-\); (c) \(\text{N}_2\text{O}_5 + \text{H}_2\text{O} \rightarrow 2\text{H}^+ + 2\text{NO}_3^-\).

Step-by-step solution

Understanding the Concept

When oxides react with water, they either form acidic or basic solutions. Metal oxides typically form basic solutions while non-metal oxides form acidic solutions. Understanding this will help us predict the products of these reactions.

Determine the Products for Each Reaction (a)

For (a), barium oxide (\(\text{BaO}\)) is a metal oxide. When it reacts with water, it forms barium hydroxide: \(\text{BaO} + \text{H}_2\text{O} \rightarrow \text{Ba(OH)}_2\). The net ionic equation will focus on the ions that are involved in the formation of this product.

Write the Dissociation Equations (a)

The product, barium hydroxide, will dissociate in water: \(\text{Ba(OH)}_2 \rightleftharpoons \text{Ba}^{2+} + 2\text{OH}^-\). Barium oxide reacts with water to produce these hydroxide ions, confirming the basic nature of the resulting solution.

Net Ionic Equation for (a)

Combining the dissociation and the product formation, the net ionic equation for (a) is: \[\text{BaO} + \text{H}_2\text{O} \rightarrow \text{Ba}^{2+} + 2\text{OH}^-\].

Determine the Products for Each Reaction (b)

For (b), cesium oxide (\(\text{Cs}_2\text{O}\)) is another metal oxide. It reacts with water to form cesium hydroxide: \(\text{Cs}_2\text{O} + \text{H}_2\text{O} \rightarrow 2\text{CsOH}\). Each \(\text{CsOH}\) will dissociate into ions.

Write the Dissociation Equations (b)

The dissociation of cesium hydroxide in water is \(\text{CsOH} \rightleftharpoons \text{Cs}^+ + \text{OH}^-\). The oxide reacting with water effectively produces these ions.

Net Ionic Equation for (b)

Thus, the net ionic equation for the reaction of \(\text{Cs}_2\text{O}\) with water is: \[\text{Cs}_2\text{O} + \text{H}_2\text{O} \rightarrow 2\text{Cs}^+ + 2\text{OH}^-\].

Determine the Products for Each Reaction (c)

For (c), dinitrogen pentoxide (\(\text{N}_2\text{O}_5\)) is a non-metal oxide. It reacts with water to form nitric acid: \(\text{N}_2\text{O}_5 + \text{H}_2\text{O} \rightarrow 2\text{HNO}_3\). Nitric acid fully ionizes in water.

Write the Dissociation Equations (c)

The dissociation of nitric acid in water is \(\text{HNO}_3 \rightleftharpoons \text{H}^+ + \text{NO}_3^-\). The formation of these ions makes the solution acidic.

Net Ionic Equation for (c)

Therefore, the net ionic equation for \(\text{N}_2\text{O}_5\) reacting with water is: \[\text{N}_2\text{O}_5 + \text{H}_2\text{O} \rightarrow 2\text{H}^+ + 2\text{NO}_3^-\].

Key concepts

Acid-Base Reactions

Acid-base reactions are essential in understanding how substances interact in water. These reactions typically involve the exchange of hydrogen ions, often resulting in the formation of water and a salt. When we think of acids and bases, we often refer to the

• strength of an acid (like hydrochloric acid) or base (like sodium hydroxide)
• how they interact with water to produce ions

Using water as a medium, acids donate hydrogen ions (\( \text{H}^+ \)), while bases provide hydroxide ions (\( \text{OH}^- \)).
This ion exchange is a hallmark of acid-base reactions. Understanding these concepts is key to predicting the behavior of metal and non-metal oxides when dissolved in water.

Metal Oxides and Water

Metal oxides are known to form basic solutions when they react with water. In these reactions:

• Metal oxides, like barium oxide (\( \text{BaO} \)), react with water to form metal hydroxides
• This process results in the formation of an alkaline solution

For example, when barium oxide reacts with water, it produces barium hydroxide (\( \text{Ba(OH)}_2 \)), which dissociates into barium ions (\( \text{Ba}^{2+} \)) and hydroxide ions (\( \text{OH}^- \)).
Certain ions like cesium in cesium oxide (\( \text{Cs}_2\text{O} \)) also follow this pattern, reinforcing the basic nature of solutions formed from metal oxides.

Non-Metal Oxides and Water

Unlike metal oxides, non-metal oxides generally produce acidic solutions when reacting with water. This results in the formation of acids. Consider dinitrogen pentoxide (\( \text{N}_2\text{O}_5 \)):

• It reacts with water to yield nitric acid (\( \text{HNO}_3 \)), a strong acid
• This acid fully ionizes in water, releasing hydrogen ions and nitrate ions (\( \text{NO}_3^- \))

The ability of non-metal oxides to form acids through this interaction highlights their significant role in acid rain and environmental science.
In general, recognizing the behavior of non-metal oxides with water aids in understanding various chemical processes, including those impacting our environment.