About the ads

  1. Check out PREMED.me!
    Offers FREE service to help premeds manage their applications and MCAT study calendars and identify schools to target.

How does surface pressure increase with a leak in vacuum distillation apparatus?

Discussion in 'MCAT Study Question Q&A' started by libraryismyhome, Apr 30, 2011.

  1. SDN is a nonprofit organization. Services are made possible through the generous support of SDN members and sponsors. Thank you.
  1. libraryismyhome

    libraryismyhome

    Joined:
    Mar 6, 2010
    Messages:
    658
    Status:
    Medical Student
    SDN 2+ Year Member

    SDN Members don't see this ad. (About Ads)
    This is AAMC 3 BS #114 question.

    If there is a leak in vacuum distillation apparatus, I thought some of the gases would escape which would decrease the pressure in the apparatus, so that the boiling point would decrease.

    But the answer said that if there is a leak, the surface pressure increases which increases the boiling point.
  2. loveoforganic

    loveoforganic -Account Deactivated-

    Joined:
    Jan 30, 2009
    Messages:
    4,229
    SDN 2+ Year Member
    Vacuum distillation apparatus doesn't build up significant pressure relative to the atmosphere. With a leak, you actually have a leak in (i.e., you now have atmospheric pressure pushing on the liquid in your system).
  3. libraryismyhome

    libraryismyhome

    Joined:
    Mar 6, 2010
    Messages:
    658
    Status:
    Medical Student
    SDN 2+ Year Member

    a trenchant answer! thank you. :thumbup:
  4. xlcooplx

    xlcooplx

    Joined:
    Jan 11, 2011
    Messages:
    159
    Location:
    First Neck Road, SC
    Status:
    Medical Student
    SDN 2+ Year Member
    Exactly. Remember the purpose of using vacuum filtration. Vacuum filtration reduces the pressure inside of the apparatus to be below that of atmospheric pressure. In doing so, we are able to distill liquids with otherwise high boiling points at a significantly lower temperature because the internal pressure of the system has decreased. If there is a leak in the vacuum apparatus, then you are allowing atmospheric pressure to act on the gas vapors in the system. In doing so, the boiling point will rise.

Share This Page


About the ads