Problem 42 - Chemistry and Chemical Reactivity

Question

The element below aluminum in Group \(3 \mathrm{A}\) is gallium, and there are numerous similarities in the chemistry of these two elements. For example, the hydroxides of both elements are amphoteric. A consequence of this is that both gallium hydroxide and aluminum hydroxide (a) are insoluble in water (b) dissolve only in acid (c) dissolve only in base (d) dissolve in acid and in base

Step-by-Step Solution

Answer

(d) They dissolve in acid and in base.

Step 1: Understand the term amphoteric

An amphoteric substance is one that can react with both acids and bases. When you are determining the behavior of the hydroxides of gallium and aluminum, remember that amphoteric substances have this dual capability.

Step 2: Analyze the amphoteric property

Since both gallium hydroxide and aluminum hydroxide are amphoteric, they will not only react with acids, but also with bases. This is a key characteristic of amphoteric compounds which participate in reactions by donating or accepting protons or electrons with acids and bases.

Step 3: Evaluate the options

The problem asks us to identify the common behavior of gallium hydroxide and aluminum hydroxide due to their amphoteric nature. Looking at the options provided: - Option (a) asserts they are insoluble in water. This is true to a certain extent as they chiefly display solubility in acidic or basic environments. - Option (b) suggests they dissolve only in acids, which ignores the amphoteric nature that allows them to also dissolve in bases. - Option (c) implies they dissolve only in bases, neglecting solubility in acids. - Option (d) states they dissolve in both acids and bases, which aligns perfectly with their amphoteric characteristic.

Step 4: Reach the Conclusion

Based on our analysis that gallium hydroxide and aluminum hydroxide are amphoteric, they are capable of dissolving in both acidic and basic solutions. Hence, the correct option that addresses this characteristic is (d).

Key Concepts

Gallium Hydroxide

Gallium hydroxide Gallium hydroxide (Ga(OH)_3) is a noteworthy amphoteric compound. This means that it can react with both acidic and basic solutions effectively. Generally insoluble in water, it does not dissolve easily on its own. This property makes gallium hydroxide quite intriguing because it showcases its flexibility by reacting with different chemical environments.
Some of the distinguishing features of gallium hydroxide are:

• Its ability to act as both an acid and a base, making it amphoteric.
• Reactivity with acids leads to the formation of gallium salt solutions.
• Reactivity with bases results in gallate ions.

In real-world applications, these characteristics are especially valuable. They allow gallium hydroxide to be utilized effectively in diverse chemical processes.

Aluminum Hydroxide

Aluminum Hydroxide Aluminum hydroxide Aluminum hydroxide (Al(OH)_3) is very similar to gallium hydroxide in terms of its amphoteric behavior. Known for being white in color, it is also generally insoluble in water, like gallium hydroxide. When it does interact with acids and bases, however, it becomes soluble by forming compounds with them.
Key attributes of aluminum hydroxide include:

• Its amphoteric nature - it can dissolve in both acidic and basic environments.
• The formation of aluminum salts when reacted with acids.
• Creation of aluminate ions when reacted with strong bases.

These properties not only make aluminum hydroxide helpful in many industrial processes but also highlight its role in fields like medicine and water purification.

Reactivity with Acids and Bases

Reactivity with Acids and Bases The amphoteric character of compounds such as gallium hydroxide and aluminum hydroxide is what allows them to interact and dissolve in both acids and bases. This dual reactivity is fascinating because it exemplifies a balance between acidic and basic behaviors in chemistry.
When an amphoteric compound like gallium hydroxide or aluminum hydroxide reacts with an acid, it typically donates hydroxide ions, leading to a more cohesive solution where the metal ions are solvated.
Conversely, when these compounds encounter strong base solutions, they tend to accept protons, thus forming complex ions like gallates or aluminates.
These activities underscore the adaptability of amphoteric substances and are crucial for applications involving the neutralization of pH, catalysis, and material science.