## Qwerty90 3 years ago Which of the following changes has a decrease in entropy?

1. Qwerty90

hg N2O4 (g) 2NO2 (g) 3O2 (g) + 2KCl (s) 2KClO3 (s) C2H5OH (l) + 3O2 (g) 2CO2 (g) + 3H2O (g) H2O (l) H2O (g)

2. Mani_Jha

Do you know what a decrease in entropy means?

3. Qwerty90

Yes. It means that the amount of randomness decreases eighter by the movement or amount of moleues

4. Qwerty90

But its hard to tell from these equATIONS

5. Mani_Jha

Now, see if I lump two free molecules(which had a lot randomness) into a single molecule of more weight, which will have more entropy(randomness), the two free molecules, or the resultant single heavier molecule? Did you get my question?

6. Qwerty90

Uhh. are you asking which would be heavier

7. Qwerty90

I get what you're saying in the first half but when you asked it looks like you left out th word "what" so I couldn't really see what you are asking

8. Mani_Jha

No, I am asking which one will move more easily i.e which will have more randomness. Of course, the single molecules formed as a product will be heavier than either of the reactants.

9. Qwerty90

Is it this one? 3O2 (g) + 2KCl (s) 2KClO3 (s)

10. Mani_Jha

Yes. Do you understand why? Two reactants combine to form a single product of more weight. This restricts movement.(It is difficult for a heavier particle to move). So, it has less entropy

11. Qwerty90

OHhh I got ya. So if it decreases we are looking for more of a solid or a more combined molecule. And if it increases we are looking for more seperation. Is this right>

12. Mani_Jha

Yes, exactly.

13. Qwerty90

one thing...Which of the following changes will always be true for a spontaneous reaction? Would this be 1deltaG

14. Qwerty90

Im sorry -1deltaG

15. Mani_Jha

Yes, whenever Gibb's Free Energy is negative, the reaction is spontaneous. Because then the change in enthalpy is negative. This means that the products are more stable than the reactants.

16. Qwerty90

And would boiling water be an example of an increase in entropy? or these filtering sand out of a sample of water synthesizing water from hydrogen and oxygen

17. Mani_Jha

Boiling water converts liquid water into gaseous water vapour. As the particles in a gas have more randomness, there is an increase in entropy. Synthesizing water from hydrogen and oxygen is again one case where two molecules lump together to form a heavier molecule. So what do you think?