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Photon336

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  1. Photon336
    • one year ago
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    Attached here

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  2. Photon336
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    @Rushwr

  3. Photon336
    • one year ago
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    223. Vapor pressure and temperature are proportional b/c when you raise the temperature the fraction of molecules that can escape into the gaseous phases increases and therefore the vapor-presure goes rises. Hydrogen bonding, this would affect vapor pressure because it is a property that depends on Intermolecular forces. the presence of hydrogen bonding between molecules would require more energy to break those bonds and allow those molecules to get into the gaseous phase. (i'm guessing that this would lower the vapor pressure). The presence of solutes is a colliagitive property, one that depends on the number of molecules one dissolves into a solvent, rather than their identity. adding a solute would technically raise the boiling point because it would just take longer for those molecules to go from (l)-->(g). I think it would affect vapor pressure. External pressure: the vapor pressure continues to rise until it equals the external pressure, and boiling occurs. although the external pressure will dictate when a substance will boil, it does not have a direct effect on the vapor pressure in my opinion. I believe that the answer is External pressure

  4. Photon336
    • one year ago
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    @Bozhena thoughts on 221?

  5. anonymous
    • one year ago
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    I try to figure out which between A and D

  6. anonymous
    • one year ago
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    222. is D, Cus Carbonates, Phosphates,sulfides are insoluble

  7. Photon336
    • one year ago
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    224. This question relates to a gases solubility in water.. @rushwr thoughts? not sure..about gas suability in liquids? \[HCl _{g} + H _{2}O(l) ---> H _{3}O ^{+} + Cl- \]

  8. Photon336
    • one year ago
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    224. To me why would HCL exist primarily as molecules? it would most likely be H+ + Cl- to me A was false. B I believe that this is that answer because you've have in situ all the gas dissolved and reacted already so you would also have Cl- ions in your solution. C. from the formula I wrote above hydronium ion concentration would go up. Cl- does not raise the pH i think it's B.

  9. Photon336
    • one year ago
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    @Bozhena you were right 222. D 223. A 224. B

  10. Photon336
    • one year ago
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    how do we figure out whether a gas is soluble in a solution? (it's like dissolves like right?)

  11. anonymous
    • one year ago
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    The dissolving of a gas in water depends on the interaction between the molecules of the gas and the water molecules. As water is polar and HCl too they will interact with eachother

  12. Photon336
    • one year ago
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    Ah I see, the last question we have is 221, I will post some more for us to discuss

  13. anonymous
    • one year ago
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    221. D.

  14. Rushwr
    • one year ago
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    I'm sorry i couldn't join the convo sum problem with my internet connection @Photon336

  15. anonymous
    • one year ago
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    Here's a great example of how the external pressure is EXTREMELY important to vapor pressure! https://www.youtube.com/watch?v=pOYgdQp4euc

  16. anonymous
    • one year ago
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    that's so cool. But i dont get why it freez

  17. Photon336
    • one year ago
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    @Woodward that's a great video, how would you describe this?

  18. anonymous
    • one year ago
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    It freezes because of this fine equation: PV=nRT We know the room was kept at a constant temperature, the volume of that glass thing covering it was a constant, but they lowered the pressure! What does that mean? They had to have removed particles, it's the only thing left free in the equation! \[P=n*\frac{RT}{V}\] So now what does removing particles do? Well now there's no longer anything for molecules in the water to hit up against, there's no more atmosphere! |dw:1438540793060:dw| The water molecules are now free to escape, there's no longer a counteracting external pressure. You gotta realize that water molecules are basically weightless on their own, so once they leave they leave into the air and the get sucked out with the pump allowing more to keep bouncing out. But what's left? Just the slow moving water molecules. So really most of the heat left with the ones that bounced out. Keep in mind that they froze into a solid but they're still about 273 Kelvin above absolute zero, so they're still warm in some sense!

  19. anonymous
    • one year ago
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    Anyways when you said you thought the answer was A, I knew it couldn't be further from the truth and had to show you something so you couldn't forget haha :P

  20. anonymous
    • one year ago
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    Here's another good video I just found of it if you're still curious, I don't want to distract you too much from studying haha: https://www.youtube.com/watch?v=I5mkf066p-U

  21. sweetburger
    • one year ago
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    What did you guys come up with as the answer for 223

  22. sweetburger
    • one year ago
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    Did you guys choose A? or did you come to another answer choice.

  23. Photon336
    • one year ago
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    @sweetburger I chose A, but @Woodward gave a better interpretation so I'm reading that now

  24. sweetburger
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    My textbook states that vapor pressure is independent of atmospheric pressure.

  25. Photon336
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    Haven't worked out 221. yet whoever has an answer please justify!

  26. sweetburger
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    atmospheric/external pressure...

  27. sweetburger
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    For 221 i do not think the answer could be either b or c due to the common ion effect

  28. Photon336
    • one year ago
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    the example woodward gives (to my knowledge) demonstrates the opposite.. like if you lower the external pressure seems to have an effect

  29. sweetburger
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    Thats in a vacuum isnt it?

  30. Photon336
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    yeah

  31. sweetburger
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    yeah...

  32. sweetburger
    • one year ago
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    Were not looking to completely remove the atmosphere were saying if the atmospheric pressure were to change to increase/decrease would it have an effect on the vapor pressure of the liquid.

  33. Photon336
    • one year ago
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    like if i boiled water on top of a mountain, vs at sea level, the BP would be different.

  34. sweetburger
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    Yea same idea as you.

  35. Photon336
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    yeah.. guys how do i QUOTE someone?

  36. sweetburger
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    What I meant to say is that it is easier to boil water on the top of a mountain than it is to boil water at sea level. *sorry previous post had a typo

  37. anonymous
    • one year ago
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    Right right, I am confusing the stuff, vapor pressure is not affected by external pressure. The reason it boils is because the vapor pressure doesn't depend on external pressure. It was always the same, it's just the external pressure it was pushing against has been removed. The answer is definitely A. Haha sorry for the confusion.

  38. sweetburger
    • one year ago
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    Yes, perfectly explained.

  39. Photon336
    • one year ago
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    I always thought that boiling occurred when they vapor pressure = external pressure, you mentioned that the external pressure was removed? once that happens.

  40. Photon336
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    so.. the external pressure has been overcome once boiling has occurred?

  41. anonymous
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    Exactly. So you could either give the liquid enough energy so that the molecules are moving fast enough that they can "jump off" into the air or you can remove some of the air and there's nothing holding them in anymore

  42. anonymous
    • one year ago
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    |dw:1438542280001:dw|

  43. sweetburger
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    So at the top of the mountain it just takes less water molecules to escape the surface to cause the liquid to boil.

  44. anonymous
    • one year ago
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    It takes less heat, not less water molecules. So one molecule of water takes less energy to leave the cup of water into the air while on a mountain but if you were down lower where the pressure is higher, then it takes more heat to make that same molecule escape the rest of the water.

  45. Photon336
    • one year ago
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    Pressure goes down so, lower temp = less energy

  46. Photon336
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    maybe I over simplified that

  47. anonymous
    • one year ago
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    Heat is Energy @sweetburger Yeah @Photon336 I don't know, since lower temp = less energy is always true because temperature is average kinetic energy of the particles, saying lower temperature means lower average kinetic energy.

  48. sweetburger
    • one year ago
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    @Woodward wasnt disputing that

  49. anonymous
    • one year ago
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    Yeah I was just trying to clarify cause I sorta just said "energy" and "heat" separately but I didn't want to confuse you haha

  50. Photon336
    • one year ago
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    energy/heat not necessarily the same, i believed i confused that with temperature

  51. sweetburger
    • one year ago
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    I was saying it takes less water molecules to reach the same atmospheric pressure and I was inferring that it is known that it takes heat for the water molecules to escape the surface of the liquid.

  52. sweetburger
    • one year ago
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    In regards to this post "So at the top of the mountain it just takes less water molecules to escape the surface to cause the liquid to boil. "

  53. Photon336
    • one year ago
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    okay.. that makes sense

  54. Photon336
    • one year ago
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    @Woodward the first video you showed. was the pressure decreased or increased? trying to look at the graph @Bozhena posted

  55. anonymous
    • one year ago
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    P decreased

  56. Photon336
    • one year ago
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    started off with liquid water, at constant volume, I see the pressure must have deceased to get it to solid ice eventually

  57. Photon336
    • one year ago
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    but in the first part it evaporated went from liquid to gas so under those conditions i'm assume you would have to increase the pressure to do that?

  58. Photon336
    • one year ago
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    Just trying to make sense of this and connect it to the phase diagram for water.

  59. anonymous
    • one year ago
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    I don't know if this graph completely explains the video, because this graph is from equilibrium thermodynamics but here we had an open system (we were removing particles from the system with the vacuum) so that's how we were able to maintain constant temperature and freeze it at room temperature. |dw:1438543223019:dw| See that's the line of constant temperature we travelled down

  60. anonymous
    • one year ago
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    Wait.... I don't think what I put is right hahaha Oh well I'll leave it up maybe we can find the error

  61. Photon336
    • one year ago
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    Well you decreased the the pressure at a low temperature (assuming under conditions of constant volume)

  62. Photon336
    • one year ago
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    no wait

  63. Photon336
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    shouldn't the pressures be reversed?

  64. Photon336
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    we started off with liquid so we would have had to increase the pressure under those conditions..

  65. anonymous
    • one year ago
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    Oh she flipped liquid with gas that's all: http://christophercapp.com/wp-content/uploads/2013/09/Triple-Point-Diagram-011.jpg

  66. anonymous
    • one year ago
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    My mistake, it too confusing, the diagram do not explain the phenomenon. So the best explenation is @Woodward. As the molecure had no more pressure they are free to go away. But to turn in to the gas they need to use they own evergy, so after some time than they boiling they loose a lot of Kinetic Energy and freez.

  67. anonymous
    • one year ago
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    |dw:1438543545122:dw| All good we're all confused here this is kinda fun figuring this out together @Bozhena @Photon336 @sweetburger

  68. Photon336
    • one year ago
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    yes haha

  69. Photon336
    • one year ago
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    Guys I will post another one and close this out soon

  70. Photon336
    • one year ago
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    last thing so this graph can't explain the phenomena for the vacuum totally because this is for an open system?

  71. anonymous
    • one year ago
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    nice ;) Sorry for the mess

  72. anonymous
    • one year ago
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    no, cuz it do not consider the lost of energy, in out case lost of kinetic energy.

  73. Photon336
    • one year ago
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    That's good to know

  74. Photon336
    • one year ago
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    yeah cuz we kept temperature constant

  75. Photon336
    • one year ago
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    Will post another question =D

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