What distinguishes a physical explosion from a chemical explosion?

The distinction between physical explosions and chemical explosions primarily lies in the mechanisms that drive them. A physical explosion is characterized by rapid gas expansion, which occurs without any accompanying chemical reaction. This can involve scenarios such as the rupture of a pressurized vessel or the explosion of a gas cloud when ignited, leading to a sudden release of energy that generates shock waves.

In contrast, chemical explosions are driven by exothermic chemical reactions that produce gases and heat, resulting in an increase in pressure and volume. While both types of explosions can occur suddenly and cause destruction, the key feature of a physical explosion is its dependence solely on physical phenomena, such as the behavior of gases under pressure or the physical state of materials.

The other options do not effectively define the distinction. For instance, the premise that physical explosions are caused by chemical reactions is incorrect, because these explosions do not involve any chemical change. Similarly, the assertion that chemical explosions do not involve gas expansion overlooks the fact that they often produce gas as a byproduct of the reaction, leading to significant pressure increases. Lastly, claiming that chemical explosions can only occur at low pressure is misleading, as these reactions can occur across a wide range of pressures, often in high-pressure environments.