Final answer:
Spontaneous phenomena are processes that occur naturally without added energy, such as melting ice, rusting iron, or heat transfer from hot to cold objects. These often involve changes in entropy and energy within the system, with entropy acting as a key driving force.
Step-by-step explanation:
Spontaneous phenomena refer to the natural occurrence of physical or chemical processes without the need for added energy. Some examples of spontaneous processes include the melting of an ice cube at room temperature, where heat transfers from the surroundings to the ice, causing it to melt. Another example is iron rusting in a moist atmosphere, a chemical change where iron reacts with water and oxygen to form rust.
Also, the diffusion of helium from a balloon is spontaneous, involving the redistribution of He atoms from an area of higher concentration within the balloon to an area of lower concentration outside, usually resulting in the balloon deflating overnight.
A spontaneous reaction often leads to an increase in entropy and a decrease in energy within the system. On the other hand, spontaneous processes can also involve energy redistribution, like the transfer of heat from a hot object to a colder one until they reach equilibrium. Entropy serves as a driving force in spontaneous processes, favoring changes that increase the disorder or randomness of a system.