Which would have greater entropy?

1. Br2 or 2Br?
2. CH4 at 25 Celsius or CH4 at 45 Celsius?
3. 1 mol CH4 in 1-L H2O or 1 mol CH4 in 2-L H2O?

This is a very good question. I will be happy to critique your thinking.

I would say first that Br2 would have more than 2Br because don't individual atoms have an entropy of 0? The other two, I have no idea honestly! Please help me with those!

Br2 has more unavailable energy than the atoms, so its entropy is higher.

Use that definition on b.

On c, which has the greater dispersal of CH4 molecules? http://en.wikipedia.org/wiki/Entropy

You're on the right track with your thinking!

For the first question, comparing Br2 and 2Br, individual atoms do indeed have an entropy of 0 because they are in the most ordered state possible. In this case, Br2 consists of two atoms bonded together, so it has more unavailable energy than the individual atoms. Therefore, Br2 would have greater entropy than 2Br.

Moving on to the second question, comparing CH4 at 25 Celsius and CH4 at 45 Celsius. Entropy generally tends to increase with temperature because higher temperatures correspond to greater molecular motion and disorder. So, CH4 at 45 Celsius would have higher entropy than CH4 at 25 Celsius.

Lastly, for the third question, comparing 1 mol of CH4 in 1-L H2O and 1 mol of CH4 in 2-L H2O. Entropy is related to the dispersal or distribution of molecules. In this case, the ratio of CH4 to H2O molecules is the same in both cases (1:1), but the volume of the solvent (water) changes. Having a larger volume of water would allow for more random motion and greater dispersal of molecules, leading to higher entropy. Therefore, 1 mol of CH4 in 2-L H2O would have greater entropy than 1 mol of CH4 in 1-L H2O.

Remember, entropy is a measure of disorder or randomness in a system. When comparing different scenarios, look for factors that contribute to greater disorder or dispersal of molecules, as these would lead to higher entropy.