Question

In the 17th century, Aristotle made note of the fact that silver chloride turned darker under exposure to light.

Option 1: True
Option 2: False

Answer 1

The statement about Aristotle noting silver chloride's photosensitivity is false, as this observation was made by Johann Heinrich Schulze. The original salt in the solution added with silver nitrate, forming a pale yellow precipitate, was likely an iodide, as shown by a follow-up test with chlorine water and carbon tetrachloride resulting in a purple solution.

Step-by-step explanation:

The statement about Aristotle making note of the fact that silver chloride turned darker under exposure to light in the 17th century is False. Aristotle lived in Ancient Greece in the 4th century B.C., not the 17th century. The observation of silver chloride's photosensitivity was made by Johann Heinrich Schulze in 1727, who found that a mixture of silver nitrate and chalk darkened when exposed to light, laying the groundwork for the development of photography.

Regarding the question about the test tube with a clear, colourless salt solution, the original salt was likely an iodide, considering the result of the reaction with silver nitrate produced a pale yellow precipitate, which is characteristic for silver iodide. Adding chlorine water and carbon tetrachloride formed a purple solution, indicating the presence of free iodine, which occurs when chlorine displaces iodine from the iodide. The balanced chemical reaction between the salt and silver nitrate is likely:

• AgNO3 (aq) + KI (aq) → AgI (s) + KNO3 (aq)