Question

\(\mathrm{NaOH}\) is a strong electrolyte, and \(\mathrm{CH}_{3} \mathrm{OH}\) is a nonelectrolyte. How does their dissociation in water differ?

Short answer

\text{NaOH} completely dissociates into \text{Na}^+ and \text{OH}^- ions, while \text{CH}_3\text{OH} remains as molecules in water.

Step-by-step solution

- Understanding Electrolytes

Recognize that a strong electrolyte like \(\text{NaOH}\) completely dissociates into ions in water. Conversely, a nonelectrolyte like \(\text{CH}_3\text{OH}\) does not dissociate into ions; instead, it remains as molecules.

- Dissociation Process

Write the dissociation equation for sodium hydroxide (NaOH): \[\text{NaOH} \rightarrow \text{Na}^+ + \text{OH}^-\] This shows that each mole of NaOH separates completely into sodium ions (Na\textsuperscript{+}) and hydroxide ions (OH\textsuperscript{-}).

- Non-Dissociation of Methanol

Since \(\text{CH}_3\text{OH}\) is a nonelectrolyte, it does not dissociate in water. Thus, it stays as intact \(\text{CH}_3\text{OH}\) molecules when dissolved.

- Comparing the Two

Summarize the differences: \(\text{NaOH}\) dissociates completely into ions in water, making it a strong electrolyte. \(\text{CH}_3\text{OH}\) does not dissociate, behaving as a nonelectrolyte.

Key concepts

strong electrolytes

Strong electrolytes are substances that completely dissociate into ions when dissolved in water. This means that when a strong electrolyte like sodium hydroxide (\text{NaOH}) is added to water, it separates entirely into its constituent ions. For \text{NaOH}, the dissociation process can be represented by the equation: \[ \text{NaOH} \rightarrow \text{Na}^+ + \text{OH}^- \] This indicates that each unit of \text{NaOH} produces one sodium ion (\text{Na}^+) and one hydroxide ion (\text{OH}^-), both of which are free to move independently in the solution. As a result, solutions of strong electrolytes conduct electricity very well due to the presence of these free ions. Common examples of strong electrolytes include many salts, acids, and bases.

dissociation in water

Dissociation in water is the process by which a compound separates into ions when dissolved in water. This phenomenon is crucial for understanding why certain substances can conduct electricity in solution. When we talk about strong electrolytes, their dissociation in water is complete. For instance, the dissociation of NaOH in water is represented as: \[ \text{NaOH} \rightarrow \text{Na}^+ + \text{OH}^- \] Here, the ionic bonds between \text{Na}^+ and \text{OH}^- are broken, and the two ions become surrounded by water molecules. This allows them to move freely within the solution, enabling electrical conductivity. The degree of dissociation differentiates strong electrolytes from weak ones and nonelectrolytes. Strong electrolytes dissociate entirely, resulting in a high concentration of ions in the solution.

nonelectrolytes

Nonelectrolytes are substances that do not dissociate into ions when dissolved in water. Instead, they remain as intact molecules. A common example of a nonelectrolyte is methanol (\text{CH}_3\text{OH}). When \text{CH}_3\text{OH} dissolves in water, it stays as whole \text{CH}_3\text{OH} molecules: \[ \text{CH}_3\text{OH} \rightarrow \text{CH}_3\text{OH (in water solution) } \] This means that there are no free ions present in the solution, making it unable to conduct electricity. Unlike strong electrolytes, nonelectrolytes do not participate in ionic conduction, which is why solutions containing only nonelectrolytes do not conduct electricity. Understanding the behavior of nonelectrolytes helps clarify why not all solutions can carry an electric current.