An example of a substance that does not change directly from solid to gas when heated is
Answer Details
When discussing the process of substances changing states, some substances can transition directly from a solid to a gas without passing through a liquid state. This process is called sublimation. However, not all substances exhibit this behavior. Let's examine the substances provided:
Ammonium chloride (NH4Cl): This substance can sublimate, meaning it can go directly from a solid state to a gaseous state when heated.
Iodine (I2): Iodine is known for sublimating as well. When iodine crystals are heated, they turn directly into a violet gas without becoming a liquid.
Calcium carbonate (CaCO3): This substance does not sublimate. Instead, when heated, it decomposes, releasing carbon dioxide gas and leaving calcium oxide as a residue. Therefore, it does not directly transition from a solid to a gas.
Sulfur (S8): This substance melts into a liquid before it evaporates, so it doesn't sublimate.
In conclusion, calcium carbonate (CaCO3) is the substance that does not change directly from a solid to a gas when heated, as it undergoes a decomposition process instead.