1. Dismiss Notice
  2. Guest, be sure to check out How To Get Into Dental School, our free downloadable PDF with step-by-step details for dental school applicants!
    Dismiss Notice
  3. Download free Tapatalk for iPhone or Tapatalk for Android for your phone and follow the SDN forums with push notifications.
    Dismiss Notice

Gchem

Discussion in 'DAT Discussions' started by Lonely Sol, Apr 26, 2007.

  1. Lonely Sol

    Lonely Sol cowgoesmoo fan!
    10+ Year Member

    Joined:
    Dec 13, 2005
    Messages:
    684
    Likes Received:
    0
    Status:
    Pre-Dental
    A sample of air held in a graduated cylinder over water has a volumne of 88.3ml at a temperature of 18.5 degree C. and a pressure of 741nm. What would the volume of the air be if it were dry and at the same temperature and pressure?
     
  2. Note: SDN Members do not see this ad.

  3. Nasem

    2+ Year Member

    Joined:
    Aug 30, 2006
    Messages:
    1,008
    Likes Received:
    0
    Status:
    Pre-Medical
    This is classic PV = nRT,
    Since n, R, and T are constancts in this, we leave them out and put

    PiVi = PfVf

    You know your initial pressure and volume,
    you also know your final pressure (since it says constant), just need to solve for Vf
     
  4. orthdent786

    orthdent786 Junior Member
    5+ Year Member

    Joined:
    Dec 12, 2005
    Messages:
    71
    Likes Received:
    0
    Status:
    Pre-Dental
    if thats the case then Vi=Vf b/c the pressures just cancel out, i'm not sure if that is the equation we are supposed to use? maybe someone else can help?
     
  5. doc toothache

    10+ Year Member

    Joined:
    Jan 17, 2006
    Messages:
    8,027
    Likes Received:
    2,168
    Status:
    Dentist
    The (vapor) pressure contributed by water at 18.5 degree C is about 20mm. It needs to be subtracted from 741mm then use P1V1=P2V2.
     
  6. infernobutterfl

    infernobutterfl Pyro user
    7+ Year Member

    Joined:
    May 26, 2005
    Messages:
    121
    Likes Received:
    0
    we are supposed to know the vapor pressure of water?? o_O
     
  7. DentalKitty

    5+ Year Member

    Joined:
    Mar 12, 2007
    Messages:
    202
    Likes Received:
    0
    Status:
    Pre-Dental
    No, I think it would be provided for you especially since VPs are temp dependent so you'd have to memorize so many. The only one I know is H2O at 100 deg C = 760mm because at the boiling point VP = atmospheric pressure. That would work for any substance at its BP and 1atm I believe.
     

Share This Page