Which statement best explains why the dissolving of NaCl (table salt) in water is NOT considered a chemical change?

• A. The salt undergoes a change in its chemical formula to form HCl and NaOH.
• B. The dissolving of salt in water is irreversible, which is a characteristic of chemical changes.
• C. No new substances are formed; NaCl dissociates into Na^+ and Cl^- ions, but the chemical composition remains the same.
• D. The process produces a gas, indicating a chemical reaction.

Answer: (C)

Verified step by step guidance

1. Understand the difference between a physical change and a chemical change: A chemical change results in the formation of new substances with different chemical formulas, while a physical change involves a change in the state or appearance without altering the chemical identity.
2. Recognize that when NaCl dissolves in water, it dissociates into its ions: NaCl (s) \rightarrow Na^{+} (aq) + Cl^{-} (aq). This process separates the compound into ions but does not change the chemical formula of the original substance.
3. Note that no new substances are formed during the dissolving process; the Na^{+} and Cl^{-} ions are simply dispersed in water, maintaining their original chemical identities.
4. Recall that physical changes are generally reversible, such as evaporating the water to recover solid NaCl, which supports that dissolving salt in water is a physical change, not a chemical one.
5. Conclude that the correct explanation is that no new substances are formed during the dissolving of NaCl in water, so it is not considered a chemical change.