Final answer:
A spontaneous reaction occurs naturally under specific conditions without external energy, while a non-spontaneous reaction requires external energy input. Examples include freezing of water below freezing point (spontaneous) and a ball thrown into the air (non-spontaneous).
Step-by-step explanation:
In the realm of chemistry, a spontaneous reaction is one that occurs naturally under certain conditions without the need for continuous external energy. On the other hand, a non-spontaneous reaction requires external energy to occur. For example, liquid water freezing below its freezing point is spontaneous because it happens naturally at low temperatures. Conversely, water will not freeze above its freezing point without an input of energy, making this non-spontaneous. The combustion of gasoline is another spontaneous process, as it releases energy and occurs naturally once initiated. In contrast, a ball thrown into the air is non-spontaneous as it requires external force and will not continue without continual energy input. Similarly, a raindrop falling to the ground is a spontaneous process since it's driven by gravity. Iron rusting in a moist atmosphere is also spontaneous due to the tendency to reach a lower energy, more stable, oxidized state. Lastly, kinetic stability refers to the fact that some processes, like the oxidation of plastics, occur spontaneously but at such slow rates that observable changes may take a very long time to become apparent.