Final answer:
Observing a color change, forming a precipitate, and evolving gas are evidences of the formation of new substances. A white precipitate formation indicates a chemical reaction between hydrochloric acid and silver nitrate,chloride. A pale yellow precipitate with added chlorine water and carbon tetrachloride suggests the presence of iodide ions.
Step-by-step explanation:
The evidence to determine if new substances with new properties were formed when hydrochloric acid was added to a silver nitrate solution includes observing any color change, formation of precipitate, or evolution of gas.
When hydrochloric acid reacts with silver nitrate, a white precipitate of silver chloride is formed, indicating a chemical reaction has occurred. The balanced equation for the reaction is:
AgNO3(aq) + HCl(aq) → AgCl(s) + HNO3(aq)
If the original solution contained a salt that forms a pale yellow precipitate with silver nitrate, like some bromides or iodides, and then a purple solution with chlorine water and carbon tetrachloride (CCl4), it suggests the presence of iodide ions. Thus, the salt in the original solution could be potassium iodide or sodium iodide. The precipitation helps identify the anion present in the solution due to its characteristic color and solubility properties.