Problem 10 - Biology: The Unity and Diversity of Life

Question

A salt does not release _______ in water. a. ions b. energy c. \(\mathrm{H}^{+}\)

Step-by-Step Solution

Answer

A salt does not release \\(4+\\) in water.

Step 1: Understanding the Problem

We need to determine which of the given options does not occur when a salt dissolves in water. Salts generally dissociate into ions in aqueous solutions, a step required to solve the question.

Step 2: Identifying Salt Dissolution

When a salt dissolves in water, it typically dissociates into its constituent ions. For example, table salt (NaCl) dissolves to form Na⁺ and Cl⁻ ions.

Step 3: Analyzing the Release of Energy

The process of dissolving is usually accompanied by either an absorption or release of energy, depending on the salt and the solution conditions. However, energy changes are not 'released' as a discrete substance, unlike ions.

Step 4: Considering the Release of \\(4+\\) Ions

Salts do not typically release \(4+\) ions when they dissolve. \(4+\) ions are characteristically released by acids, not salts, when dissolved in water.

Step 5: Selecting the Correct Answer

Since salts release ions and may involve energy changes during dissolution, the correct answer is that they do not release \(4+\) ions.

Key Concepts

Ions in Solution

When a salt dissolves in water, it separates into ions, which are charged particles. This is a crucial concept in chemistry known as dissociation. For example, when table salt, also known as sodium chloride (NaCl), is added to water, it splits into sodium ions (Na⁺) and chloride ions (Cl⁻). These ions freely move in the solution, allowing the solution to conduct electricity.

• Ions: Ions are atoms or molecules that have lost or gained one or more electrons, making them charged. They can be positive (cations) like Na⁺, or negative (anions) like Cl⁻.
• Dissociation: This is the process by which an ionic compound splits into its ions when dissolved in water.

Understanding this process helps explain how substances dissolve in water and why solutions can conduct electricity, an important aspect in many chemical processes.

Energy Changes

Dissolving a salt in water involves energy changes, which may either end up absorbing energy from the surroundings or releasing it. These energy changes are categorized as endothermic or exothermic, respectively.

• Endothermic Process: This occurs when energy is absorbed, resulting in the surroundings feeling cooler. An example is ammonium nitrate dissolving in water.
• Exothermic Process: This is when energy is released, causing a temperature increase in the surroundings. An example is the dissolution of calcium chloride in water.

Whether energy is absorbed or released during dissolution depends on the specific salt and the interactions between its ions and water molecules.

Acid-Base Reactions

Salt dissolution does not involve the release of hydrogen ions (H⁺), which are crucial in acid-base reactions. In chemistry, acids are substances that can release H⁺ ions when dissolved in water. A common example of an acid is hydrochloric acid (HCl), which releases H⁺ ions when it dissolves, resulting in an acidic solution.

• Acids in Solution: These substances increase the concentration of H⁺ ions when dissolved in water.
• Bases in Solution: These substances accept H⁺ ions or release hydroxide ions (OH⁻), reducing the acidity of the solution.

Unlike acids, salts do not release H⁺ ions, which is why salts are considered neutral substances in the context of acid-base chemistry.