An aqueous solution of ethanoic acid contains

Options

A. ions only
B. molecules only
C. a mixture of ions and molecules
D. glacial acetic acid

Answer

To solve the question "An aqueous solution of ethanoic acid contains what?", we can follow these steps:

### Step 1: Understand Ethanoic Acid
Ethanoic acid, also known as acetic acid (CH₃COOH), is a weak acid. This means that it does not completely dissociate into ions when dissolved in water.

**Hint:** Consider the properties of weak acids and how they behave in solution.

### Step 2: Dissociation of Ethanoic Acid
In an aqueous solution, ethanoic acid partially dissociates into its constituent ions. The dissociation can be represented by the following equilibrium reaction:

\[ \text{CH}_3\text{COOH} \rightleftharpoons \text{CH}_3\text{COO}^- + \text{H}^+ \]

This means that some molecules of ethanoic acid remain intact, while others dissociate into acetate ions (CH₃COO⁻) and hydrogen ions (H⁺).

**Hint:** Remember that in a weak electrolyte, both the undissociated molecules and the ions are present in the solution.

### Step 3: Composition of the Solution
Therefore, in an aqueous solution of ethanoic acid, we have:
- Undissociated ethanoic acid molecules (CH₃COOH)
- Acetate ions (CH₃COO⁻)
- Hydrogen ions (H⁺)

This mixture of ions and molecules is characteristic of weak acids.

**Hint:** Think about the balance between the dissociated ions and the undissociated molecules in the solution.

### Final Answer
An aqueous solution of ethanoic acid contains a mixture of undissociated ethanoic acid molecules (CH₃COOH), acetate ions (CH₃COO⁻), and hydrogen ions (H⁺).