Classify the solution properties of 1.0 M acetic acid.
a. Strong electrolyte
b. Weak electrolyte
c. Non-electrolyte
d. Pure liquid
The correct answer and explanation is :
Correct Answer: b. Weak electrolyte
Explanation:
A 1.0 M acetic acid (CH₃COOH) solution is classified as a weak electrolyte. To understand why, we need to consider what happens when acetic acid dissolves in water and how that relates to its electrical conductivity.
1. What is an Electrolyte?
An electrolyte is a substance that, when dissolved in water, produces ions and thus can conduct electricity. Electrolytes are categorized into three types:
- Strong electrolytes completely dissociate into ions in solution (e.g., NaCl, HCl).
- Weak electrolytes partially dissociate into ions (e.g., acetic acid).
- Non-electrolytes do not produce any ions (e.g., sugar, ethanol).
2. Behavior of Acetic Acid in Water
Acetic acid is a weak acid, and it partially ionizes in aqueous solution:
$$
\text{CH₃COOH} \rightleftharpoons \text{CH₃COO}⁻ + \text{H}⁺
$$
This equilibrium reaction shows that only a small fraction of the acetic acid molecules ionize to produce hydrogen ions (H⁺) and acetate ions (CH₃COO⁻). Most of the acetic acid remains in its molecular form in solution. This limited ionization is what defines it as a weak electrolyte.
3. Electrical Conductivity
Since acetic acid produces only a small number of ions in solution, it conducts electricity poorly compared to strong electrolytes. You can observe this in laboratory experiments using a conductivity apparatus: solutions of strong acids like hydrochloric acid (HCl) light up the bulb brightly, while acetic acid produces a dim glow, indicating weaker conductivity.
4. Summary
- Acetic acid is not a strong electrolyte because it does not fully dissociate.
- It is not a non-electrolyte because it does produce some ions.
- It is not a pure liquid because the question specifies a 1.0 M solution, which is aqueous, not pure acetic acid.
Therefore, 1.0 M acetic acid is best classified as a weak electrolyte.