## Photon336 one year ago Chem question

1. Photon336

IMF question

2. Photon336

Question on vapor pressure

3. Photon336

Condensation: dealing with kinetic/potential energy

4. Photon336

@Rushwr @taramgrant0543664 @Empty

5. taramgrant0543664

I'm thinking D, D and then C I think I have it in the right order

6. Photon336

condensation is $(g) \rightarrow (l)$ So i thought kinetic energy would have to go down. for the second one

7. Rushwr

For the 1st one I'll go with B

8. Photon336

@Rushwr why not D? can you explain..

9. Photon336

not saying you're wrong

10. taramgrant0543664

Yep sorry kinetic energy does decrease

11. Rushwr

cuz HCl has dipole dipole interactions

12. Photon336

ok so for the first one it is B

13. Rushwr

for the second one I'll go with D or b

14. Rushwr

not sure though

15. Photon336

|dw:1438060894240:dw| isn't this covalent bonding?

16. Photon336

Non polar covalent?

17. Rushwr

it is but they have asked us for the intermolecular interaction not the bonding type right?

18. taramgrant0543664

C2H6 is covalent bonding

19. Photon336

oh yeah... true !

20. Photon336

wouldn't that be london dispersion forces/ vanderwalls forces for c2H4?

21. Rushwr

for the last question I'll go with D

22. taramgrant0543664

I'm pretty sure D is right for that last one

23. Rushwr

yes that is london dispersion forces @Photon336

24. Photon336

Yeah I think the last one is D. let me check

25. Photon336

oh.. wait.. it's E whaaat...

26. Photon336

@Empty thoughts?

27. Photon336

Phase change, is an equilibrium process so i'm going to make a stretch and say that at an equilibrium process temperature = constant so KE stays the same. (don't quote me on that)

28. Photon336

I can't explain why Potential energy decreases.

29. Photon336

FYI If you want to see the rest of the questions i attached them here,

30. taramgrant0543664

Condensation is gas to liquid so you're creating order and energy decreases

31. Photon336

OK, but the way though of it was that if kinetic energy goes down then PE has go up KE + PE + Wf = Mechanical energy. don't know thinking that they have to be conserved. (but i'm working backwards from the answer) the say PE went down. I guess we can go on to the second question about vapor pressure. I attached the PDF to the conversation.

32. Rushwr

maybe it's like this. When a liquid is condensed all he molecules pack in to a smaller volume right? So heat is given out. That heat is given out by the potential energy having the kinetic energy unchanged.

33. Rushwr

something like that would do right?

34. taramgrant0543664

Yes it would

35. Photon336

forcing something into a smaller volume would imply a decrease in entropy

36. Photon336

But i wonder if that's the case during any phase change

37. Photon336

b/c a phase change is an equilibrium process, where t is constant, but i think that's probably the best way to explain it.. so the heat is released by the (total potential energy) going down, leaving KE unchanged?

38. taramgrant0543664

Sounds pretty good to me. I'm going to bed now so good night enjoy the rest of the question and I'll check in again with this tomorrow!

39. Photon336

will post one more question after this then I g2g

40. Photon336

I'm not sure about the vapor pressure question @Empty thoughts?

41. Empty

Hmmm Yeah I was a bit confused by this as well I was almost sure it was D but I was also fairly certain potential energy decreased as well since the distances between particles should be less as they start to bond to each other slightly. I guess I need to go look at vapor pressure and all this I'm sort of rusty I guess.

42. Photon336

I'm going to re-post the vapor pressure question tomorrow

43. Photon336

so as you go from say (s) to liquid the kinetic energy increases but PE decreases right?

44. Photon336

We didn't get to the vapor pressure question

45. sweetburger

Ok so for im assuming question 7 that you posted about the vapor pressure. I am going with answer choice d. Both I and III are correct but II increasing the volume wouldn't have any affect on the vapor pressure.

46. Photon336

7 was A. but i'm not sure as to why though. @sweetburger equilibrium vapor pressure. like I knew increasing temperature, increases vapor pressure, but isn't the equilibrium vapor pressure = external pressure/ boiling point? NOT sure. I "guess" equilibrium = temperature dependent, so if you heat up or cool down something equilibrium will change/shift

47. sweetburger

I understand how heat affects the equilibrium, but I also thought that pressure would have an affect but thinking about it now If the pressure was increased above the surface there would be no true affect on the number of molecules coming out and the number going back in.

48. Photon336

Only other thing would be if you changed the external pressure ..