* Formation of New Substances: The reaction produces carbon dioxide gas (CO₂), calcium chloride (CaCl₂), and water (H₂O). These are entirely different substances from the original reactants.
* Irreversible Reaction: The reaction is irreversible under normal conditions. You can't easily get calcium carbonate and hydrochloric acid back from the products.
* Evidence of Chemical Change: You'll observe several signs of a chemical change:
* Fizzing/Bubbling: The release of carbon dioxide gas causes fizzing.
* Heat Production: The reaction is exothermic, meaning it releases heat.
* Color Change: The solution might change color depending on the concentration of the reactants.
The Chemical Equation:
CaCO₃ (s) + 2HCl (aq) → CaCl₂ (aq) + CO₂ (g) + H₂O (l)
In summary: The reaction between calcium carbonate and hydrochloric acid results in the formation of new substances, making it a clear example of a chemical change.
