An electrolyte will yield ions by undergoing a:
Select the correct answer below:
physical change
chemical change
spontaneous change
depends on the substance
The Correct Answer and Explanation is:
The correct answer is: chemical change
Explanation:
An electrolyte is a substance that, when dissolved in water or another solvent, dissociates into ions and conducts electricity. This ion formation is not simply a physical separation but involves a chemical change.
To understand why, let’s first clarify the difference between physical and chemical changes:
- Physical Change: This change affects the form or appearance of a substance but does not alter its chemical composition. Examples include melting, freezing, dissolving a non-electrolyte like sugar in water, or breaking a piece of glass.
- Chemical Change: This involves a transformation where the substance’s chemical identity changes, typically involving breaking and forming chemical bonds. This results in new substances with different properties. Examples include combustion, rusting, and ionization of electrolytes in water.
Why ionization of electrolytes is a chemical change
When an electrolyte dissolves in water, it undergoes ionization or dissociation. This process involves breaking the chemical bonds in the compound to release free ions. For example, table salt (NaCl) dissolves in water, splitting into sodium ions (Na⁺) and chloride ions (Cl⁻): NaCl (solid)→Na+(aq)+Cl−(aq)\text{NaCl (solid)} \rightarrow \text{Na}^+ (\text{aq}) + \text{Cl}^- (\text{aq})
Here, the ionic bonds between Na⁺ and Cl⁻ in the solid salt lattice are broken, and the ions are solvated by water molecules. This dissociation involves changing the compound from a solid ionic lattice into free ions in solution — a chemical change because the original ionic compound no longer exists in its original form.
Additional points:
- The process is spontaneous because it happens naturally when the substance is placed in water, but “spontaneous change” is not the best classification because spontaneity describes thermodynamic favorability, not the nature of the change.
- Saying it “depends on the substance” is partially true—some substances are electrolytes (undergo ionization), others are nonelectrolytes (do not ionize). However, the question asks about electrolytes specifically, which always involve chemical change when yielding ions.
Summary:
- Electrolytes yield ions by breaking chemical bonds in water.
- This is a chemical change, as it alters the chemical identity.
- Physical changes only alter physical states or appearances, not chemical structures.
- Therefore, the dissociation of an electrolyte is best classified as a chemical change.