Question

Will the following oxides give acidic, basic, or neutral solutions when dissolved in water? Write reactions to justify your answers. a. \(\mathrm{Li}_{2} \mathrm{O}\) b. \(\mathrm{CO}_{2}\) c. \(\mathrm{SrO}\)

Short answer

a. Lithium oxide (\(\mathrm{Li}_{2} \mathrm{O}\)) forms a basic solution, as shown by the reaction: \[\mathrm{Li}_{2} \mathrm{O} \ + \ 2\mathrm{H}_{2}\mathrm{O} \ \rightarrow \ 2\mathrm{LiOH} \] b. Carbon dioxide (\(\mathrm{CO}_{2}\)) forms an acidic solution, as shown by the reaction: \[\mathrm{CO}_{2} \ + \ \mathrm{H}_{2}\mathrm{O} \ \rightleftharpoons \ \mathrm{H}_{2}\mathrm{CO}_{3} \] c. Strontium oxide (\(\mathrm{SrO}\)) forms a basic solution, as shown by the reaction: \[\mathrm{SrO} \ + \ \mathrm{H}_{2}\mathrm{O} \ \rightarrow \ \mathrm{Sr(OH)}_{2} \]

Step-by-step solution

Determine the type of oxide for each substance

We will determine the type of oxide for each substance. Metallic oxides are basic and non-metallic oxides are acidic. a. \(\mathrm{Li}_{2} \mathrm{O}\): Lithium oxide Lithium is a metal, so this is a metallic oxide. b. \(\mathrm{CO}_{2}\): Carbon dioxide Carbon is a non-metal, so this is a non-metallic oxide. c. \(\mathrm{SrO}\): Strontium oxide Strontium is a metal, so this is a metallic oxide.

Write reactions for each substance dissolving in water

Next, we will write the reactions for each substance dissolving in water. a. Lithium oxide (\(\mathrm{Li}_{2} \mathrm{O}\)): \[ \mathrm{Li}_{2} \mathrm{O} \ + \ 2\mathrm{H}_{2}\mathrm{O} \ \rightarrow \ 2\mathrm{LiOH} \] Since \(\mathrm{LiOH}\) is a strong base, the solution will be basic. b. Carbon dioxide (\(\mathrm{CO}_{2}\)): \[ \mathrm{CO}_{2} \ + \ \mathrm{H}_{2}\mathrm{O} \ \rightleftharpoons \ \mathrm{H}_{2}\mathrm{CO}_{3} \] Carbonic acid (\(\mathrm{H}_{2}\mathrm{CO}_{3}\)) is a weak acid, so the solution will be acidic. c. Strontium oxide (\(\mathrm{SrO}\)): \[ \mathrm{SrO} \ + \ \mathrm{H}_{2}\mathrm{O} \ \rightarrow \ \mathrm{Sr(OH)}_{2} \] Since \(\mathrm{Sr(OH)}_{2}\) is a strong base, the solution will be basic.

Determine the type of solution for each oxide

Now we have the reactions for each oxide dissolving in water, we can determine the type of solution they form: a. Lithium oxide (\(\mathrm{Li}_{2} \mathrm{O}\)) forms a basic solution. b. Carbon dioxide (\(\mathrm{CO}_{2}\)) forms an acidic solution. c. Strontium oxide (\(\mathrm{SrO}\)) forms a basic solution.

Key concepts

Metallic Oxides

Metallic oxides are compounds formed when metals react with oxygen. These oxides are generally basic in nature, which means they tend to form basic solutions when dissolved in water. For example, lithium oxide (\(\mathrm{Li}_{2} \mathrm{O}\)) and strontium oxide (\(\mathrm{SrO}\)) are metallic oxides. Both lithium and strontium are metals, and their oxides react with water to produce hydroxides, like \(\mathrm{LiOH}\) and \(\mathrm{Sr(OH)}_{2}\), respectively.

These hydroxides are characterized as strong bases in chemistry. That's because they readily dissociate in water to form \(\mathrm{OH}^-\) ions, which increase the water's basicity. Solid metallic oxides are often found in the earth's crust in the form of minerals and are typically insoluble in water until they react to form these hydroxides.

Summary:

• Formed from metals and oxygen
• Usually basic, leading to basic solutions
• Examples include \(\mathrm{Li}_{2} \mathrm{O}\) and \(\mathrm{SrO}\)

Non-Metallic Oxides

Non-metallic oxides occur when non-metals combine with oxygen. These oxides usually create acidic solutions when mixed with water. They are essential in many biological and chemical processes, including photosynthesis. Carbon dioxide (\(\mathrm{CO}_{2}\)) serves as a classic example of a non-metallic oxide. When \(\mathrm{CO}_{2}\) dissolves in water, it forms carbonic acid (\(\mathrm{H}_{2}\mathrm{CO}_{3}\)), a weak acid that slightly lowers the pH of the water, making it acidic.

Non-metallic oxides are frequently found in atmospheric gases and volcanic gases. They can pose environmental issues, such as acid rain, when combined with atmospheric moisture. The acidic properties of these oxides are utilized in various industrial and environmental applications.

Highlights:

• Contain non-metals and oxygen
• Typically yield acidic solutions
• \(\mathrm{CO}_{2}\) is a common example

Basic Solutions

Basic solutions are those that have a pH greater than 7.0. These solutions contain more \(\mathrm{OH}^-\) ions than \(\mathrm{H}^+\) ions, leading to their basic or alkaline nature. Strong bases like sodium hydroxide (\(\mathrm{NaOH}\)) and the hydroxides formed from metallic oxides like \(\mathrm{LiOH}\) and \(\mathrm{Sr(OH)}_{2}\) are examples of substances that create basic solutions.

When you dissolve a metallic oxide in water, it usually forms a metal hydroxide, which increases the \(\mathrm{OH}^-\) ion concentration. This shift in ion balance results in a basic solution. Basic solutions are commonly used in household cleaners and industrial processes due to their ability to neutralize acids and break down organic materials.

Key Points:

• pH greater than 7
• Characterized by an excess of \(\mathrm{OH}^-\) ions
• Typical products of metallic oxides

Acidic Solutions

Acidic solutions are those that have a pH less than 7.0, signaling a higher concentration of \(\mathrm{H}^+\) ions than \(\mathrm{OH}^-\) ions. These solutions arise when non-metallic oxides come into contact with water, as seen when carbon dioxide produces carbonic acid. The formation of \(\mathrm{H}_{2}\mathrm{CO}_{3}\) from \(\mathrm{CO}_{2}\) in water is a typical reaction resulting in an acidic environment.

Acidic solutions play an important role in both natural ecosystems and industrial reactions. They are used for a variety of purposes, including food preservation and metal cleaning, because they can effectively react with many different substances.

Main Features:

• pH below 7
• Result from non-metallic oxides dissolving in water
• High \(\mathrm{H}^+\) ion concentration