A helium-filled balloon spontaneously deflates overnight as He atoms diffuse through the wall of the balloon. Describe the redistribution of matter and/or energy that accompanies this process.

The term matter redistribution refers to the changes in the location and concentration of particles within a system. When a helium-filled balloon deflates, the helium atoms travel from the high-concentration environment inside the balloon to the low-concentration space outside. This movement alters the distribution of helium, reducing the number inside the balloon and increasing it in the surrounding air. Imagine a crowded room thinning out as people spread into an adjoining empty space.

It's important to note that this redistribution happens due to random motion of the atoms and does not require an external force. This process continues until a uniform distribution of helium is achieved, or there are no more helium atoms left inside the balloon, whichever occurs first.

The kinetic energy of atoms can be understood as the energy that each atom possesses due to its motion. Helium atoms inside the balloon zip around, colliding with each other and the balloon’s interior surface. As these atoms diffuse through the balloon wall and into the air, their kinetic energy is a crucial factor enabling their movement.

Understanding Diffusion

Diffusion is essentially a migration of atoms that is powered by their intrinsic kinetic energy. In our example, the helium atoms possess enough kinetic energy to overcome the barrier of the balloon wall and spread out. The energy becomes more dispersed in the external environment, much like how a drop of food coloring slowly permeates water until uniformly distributed.

An entropy change during a process indicates a transformation in the system’s disorder or randomness. When the helium atoms confined within a balloon spread out, the system’s entropy undergoes a noticeable increase. This is because entropy, a measure of disorder, rises as particles move from a highly ordered state to a more random and disordered one.

Spontaneous Processes and Entropy

In the deflation of a helium balloon, as helium atoms are initially packed together, the system is more ordered and has lower entropy. As diffusion occurs and the atoms spread into the broader environment, their arrangement becomes more random, signifying higher entropy. This increase in entropy aligns with the Second Law of Thermodynamics, which states that the total entropy of an isolated system can never decrease over time for any spontaneous process.

• A concentration gradient is essentially the difference in the concentration of a substance between two regions.
• In our balloon example, the inside of the balloon has a high concentration of helium, while the concentration outside the balloon in the surrounding air is significantly lower.
• This gradient is the driving force for diffusion, as helium atoms naturally move from an area of higher concentration to an area of lower concentration, seeking to balance out the uneven distribution.

The rate at which diffusion occurs depends on the steepness of this gradient; the steeper it is, the faster the diffusion takes place. Once the concentration gradient is eliminated — meaning the helium is evenly dispersed — the diffusion process will cease.