Final answer:
Chemists make observations about an unknown substance like a black, fine powder by noting color, texture, state, and other physical properties without tasting. These can include conducting a flame test, measuring physical properties, and noting changes when heated.
Step-by-step explanation:
When coming across a black, fine powder, safe scientific observations can be made without directly interacting with the substance in a potentially harmful or reactive way. Based on your description, chemists might observe its physical properties: color (black), texture (fine powder), and state of matter (solid). They could also assess its mass by weighing it, measure its volume by displacement in a graduated cylinder if it is not soluble, and determine its magnetic properties by bringing a magnet near it. Additionally, a flame test could be conducted by dipping a toothpick in methanol, then into the powder, and then waving the toothpick through a flame to observe any color changes, which might indicate the presence of certain metal salts. Safety precautions like working in a well-ventilated area and using protective gear are essential. However, it is critical never to taste the substance and to be cautious with reactions involving heat or flame.
Reactions can also provide valuable insights. Such observations might include a change in color, production of gas, or formation of a residue when the substance is heated. In the case of examining dust substances, laboratory experiments have distinguished between materials like graphite and extremely small diamonds through careful observation and testing. The physical appearance and any transformation upon applying heat would be noted, and all observations would be accurately recorded.