Rank these gases in order of increasing standard molar entropy:

Column preview
Smallest S Br2(g)
Second smallest S F2(g)
Second largest S I2(g)
Largest S Cl2(g)

Matching pairs
Smallest S
Second smallest S
Second largest S
Largest S

The answer is actually:

Largest: I2 (g)
Second Largest: Br2 (g)
Third Largest: Cl2 (g)
Smallest: F2 (g)

To rank these gases in order of increasing standard molar entropy, we need to consider the properties of each gas and how they relate to entropy.

Entropy is a measure of the disorder or randomness in a system. Generally, gases with more degrees of freedom have higher entropy.

1. Smallest S: F2(g)
Fluorine gas (F2) consists of two fluorine atoms bonded together. It is a diatomic molecule with a linear structure. As a result, it has relatively fewer degrees of freedom compared to the other gases in this list, making it the gas with the smallest standard molar entropy.

2. Second smallest S: Cl2(g)
Chlorine gas (Cl2) is also a diatomic molecule. However, unlike fluorine, it has two unpaired electrons in its outer shell, which allows for additional degrees of freedom. Consequently, chlorine gas has a higher entropy compared to fluorine gas.

3. Second largest S: Br2(g)
Bromine gas (Br2) is also composed of diatomic molecules. Similar to chlorine, bromine has two unpaired electrons in its outer shell, providing more degrees of freedom. Therefore, bromine gas has a higher entropy compared to both fluorine and chlorine gases.

4. Largest S: I2(g)
Iodine gas (I2) is another diatomic molecule. However, it is the largest and heaviest of the halogens, and its size leads to increased molecular motion and more degrees of freedom. Consequently, iodine gas has the highest standard molar entropy among the listed gases.

So, the ranking from smallest to largest standard molar entropy is as follows:
1. F2(g)
2. Cl2(g)
3. Br2(g)
4. I2(g)

Based on the given information, the gases can be ranked in increasing order of standard molar entropy as follows:

1. Smallest S: F2(g)
2. Second smallest S: Cl2(g)
3. Second largest S: Br2(g)
4. Largest S: I2(g)