Dissolving a salt in water is considered a physical change, while adding an acid to a substance is a chemical change. Please give me the correct answer, please.
The Correct Answer and Explanation is:
Correct Answer: True
Explanation:
Dissolving a salt in water is considered a physical change, while adding an acid to a substance often results in a chemical change. This distinction lies in whether new substances are formed and if chemical bonds are broken or formed.
When salt (such as sodium chloride) is dissolved in water, the process involves the dissociation of the salt into its ions—sodium ions (Na⁺) and chloride ions (Cl⁻). These ions become surrounded by water molecules, but no new substances are formed. The salt can be recovered through evaporation, which confirms that no chemical transformation has occurred. The identities of sodium and chloride ions remain unchanged. This makes dissolving salt a physical change because it involves a change in the state or appearance of a substance without altering its chemical composition.
On the other hand, adding an acid to a substance usually causes a chemical reaction. For example, adding hydrochloric acid (HCl) to baking soda (sodium bicarbonate, NaHCO₃) produces carbon dioxide gas (CO₂), water (H₂O), and sodium chloride (NaCl). In this case, new substances are formed, and chemical bonds are both broken and formed during the reaction. This is clear evidence of a chemical change. The original substances are no longer present in their original form.
Another example is when acid is added to metals like zinc. It produces hydrogen gas and a salt. The visible bubbling and change in substance composition are typical signs of a chemical change.
In summary, physical changes like dissolving salt do not alter the chemical makeup of the substance, and the process can often be reversed. Chemical changes, such as reactions with acids, result in the formation of entirely new substances and often cannot be reversed by simple physical means.
