Predict how the entropy of the substance is affected in each of the processes.
A. H2O(l,300K)⟶H2O(s,273K)
B. O2(g,300K)⟶O2(g,800K)
C. Ar(l)⟶Ar(g)
A. solid ice has a more rigid structure; therefore, dS decreases.
B. O2 @ 800 K has more random ways to interact with each other; therefore, dS increases.
C. Your turn. In dS problems like this remember to look at the ransomness of the molecules.
So for C, dS would increase since gas form is less structured than liquid?
Go to the top of the class.
To predict how the entropy of a substance is affected in each process, we need to understand the factors that determine entropy.
Entropy is a measure of the disorder or randomness of a system. It increases with an increase in the number of accessible states or microstates. Therefore, we can analyze each process and determine how it affects the number of microstates, which will help us predict the change in entropy.
A. H2O(l, 300K) ⟶ H2O(s, 273K)
In this process, liquid water (H2O(l)) at 300K is cooled to form solid ice (H2O(s)) at 273K. As water solidifies, the molecules become more ordered and arranged in a crystal lattice. The solid state typically has a lower entropy compared to the liquid state because the molecules have less freedom of movement. Therefore, the entropy of the substance decreases in this process.
B. O2(g, 300K) ⟶ O2(g, 800K)
In this process, gaseous oxygen (O2(g)) at 300K is heated to a higher temperature of 800K. Increasing the temperature of a gas generally increases its entropy because the molecules move more vigorously and have a greater number of available energy states. As a result, the entropy of the substance increases in this process.
C. Ar(l) ⟶ Ar(g)
In this process, liquid argon (Ar(l)) is vaporized to form gaseous argon (Ar(g)). The transition from the liquid to gas phase typically leads to an increase in entropy. In the liquid phase, the particles are more confined and restricted in their motion compared to the gas phase, where they have more freedom to move. Therefore, the entropy of the substance increases in this process.
Overall, the predicted changes in entropy for the given processes are:
A. Entropy decreases
B. Entropy increases
C. Entropy increases