Destroyer Entropy Question

[MowgliR]

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In Destroyer is asks which of the following is true. The answer was "C4H10 would have a high entropy than C3H8." I dont understand why? I understand a larger more positive deltaS means more disorder. How can you predict without given any data?



Thanks

 

[Immutef]

In Destroyer is asks which of the following is true. The answer was "C4H10 would have a high entropy than C3H8." I dont understand why? I understand a larger more positive deltaS means more disorder. How can you predict without given any data?



Thanks

C4H10 has more atoms than C3H8, and therefore more available microstates, leading to a higher entropy.

Entropy increases when:
1. temp increases
2. volume increases
3. number of independently moving particles increases.

Each of these increases entropy because on the microscopic view, they lead to an increase in microstates, or on the macrscopic scale, they allow for energy to spread out.

Given rule number 3 it is safe to say that entrpoy increases when molecular size increases. this can be explained by considering the internal motions of the atoms in the molecules. The greater the number of bonds, the greater the number of opportunities for internal motion, leading to a greater absolute entropy of the molecule.

hope this cleared up your question

 

[wall1two]

Vibration degrees of freedom:

pretend we are on a 2 dimensional coordinate grid for now.

if we have, lets say, an H-Br molecule and we have the H at the origin we can pull the Br along the x axis, along the Y axis or compress it , and pull or compress in an direction (ignore the Z axis for now) .

if we have a propane and we put the central carbon at the origin for now, we can move 2 bonds around, and we can put the other carbons in the center and move the others around, the effect is quite cumulative.

basically more bonds means another way to multiply all the possibilities of shaking a molecule around .

mathematically 3*#atoms - 6 = vibrational degrees of freedom. each atom increases the possibilities of vibration 3 fold (z y and z movements)


HBr has 0 degrees of vibrational freedom while propane has 27 degrees of freedom

 

[invictusx]

C4H10 has more atoms than C3H8, and therefore more available microstates, leading to a higher entropy.

Entropy increases when:
1. temp increases
2. volume increases
3. number of independently moving particles increases.

Each of these increases entropy because on the microscopic view, they lead to an increase in microstates, or on the macrscopic scale, they allow for energy to spread out.

Given rule number 3 it is safe to say that entrpoy increases when molecular size increases. this can be explained by considering the internal motions of the atoms in the molecules. The greater the number of bonds, the greater the number of opportunities for internal motion, leading to a greater absolute entropy of the molecule.

hope this cleared up your question

👍