Question

Qualitative Predictions about Entropy Entropy is the randomness of a system. At the molecular level, entropy can be described in terms of the possible number of different arrangements of particle positions and energies, called microstates. The more microstates the system has, the greater its entropy. Microstates depend on molecular motion. Molecules may undergo three different types of motion: translational motion, vibrational motion, and rotational motion. During translational motion, the entire molecule moves in one direction. During vibrational motion, atoms in a molecule move toward and away from one another. During rotational motion, molecules rotate or spin. The number of molecules, the space available for the molecules, and the energy available to the molecules will impact the number of microstates. Another way of looking at entropy is that the universe is moving toward a broader distribution of energy. The universe has a constant amount of energy as stated in the first law of thermodynamics. The universe started with low entropy (concentrated in the moment before the "big bang") and the entropy has since been constantly increasing by distributing this energy. Heat distribution from high temperature to low temperature is a another example of this phenomenon. Part A Rank these systems in order of decreasing entropy. Rank from highest to lowest entropy. To rank items as equivalent, overlap them. Hints HelpReset Least entropyGreatest entropy 1 mol of neon gas at 273 K and 40 L 1 mol of chlorine gas at 273 K and 40 L 1 mol of hydrogen peroxide gas at 273 K and 40 L 1 mol of neon gas at 273 K and 20 L 1/2 mol of neon gas at 273 K and 20 L 1/2 mol of neon gas at 100 K and 20 L 1/2 mol of liquid neon at 100 K The correct ranking cannot be determined. SubmitMy AnswersGive Up Incorrect; Try Again; 4 attempts r

Answer 1

Rank from highest to lowest entropy has given below

1 mol hydrogen peroxide (H2O2) gas at 273K and 40L (highest)
1 mol chlorine (Cl2) gas at 273K and 40L
1 mol neon gas at 273K and 40L
1 mol neon gas at 273K and 20L
1/2 mol neon gas at 273K and 20L
1/2 mol neon gas at 100K and 20L
1/2 mol of liquid neon at 100K (lowest)

The less the amount of disorder (or possible states) in the system the lower the entropy.
At the same conditions 1 mol of H2O2 can be more disordered than 1 mol of chlorine gas, because H2O2 has 4 atoms which could arrange themselves in various ways whereas chlorine only has 2. Neon atoms go around by themselves not in pairs like chlorine so the number of possible different states are even fewer.
The smaller the volume the less the molecules can move around which also reduces the number of possible different states. In a colder gas the molecules or atoms are not so energetic and so do not occupy so many different energetic states. A liquid is more ordered than a gas, again reducing the number of different states.