Dismiss Notice
Hey Texans—join us for a DFW meetup! Click here to learn more.

whats the empirical formula

Discussion in 'DAT Discussions' started by dentalstudent2021, Jul 31, 2015.

  1. if 4.58% H , 40.9% C and 54.52% O is given

    Molecular Mass is 264 g /ml


    KBB does it a certain way but they don't round their calculations but do exact calculations which seems a tall task w/o a calc.
     
  2. Note: SDN Members do not see this ad.

  3. RuffDay

    2+ Year Member

    Joined:
    Apr 9, 2015
    Messages:
    770
    Likes Received:
    351
    Status:
    Dental Student
    This is how I would do it.
    First we know that oxygen takes about half of the weight of the total mass. I would round the Oxygen to 50%, but remember since we are under estimating, then we should round to a higher whole number.

    50% of the molecular mass is 132g and divide that by the oxygen mass (16g) would be 8.25. Since we are underestimating, we round the oxygen to the higher whole number, 9.

    With 120g left after subtracting the molecular weight of oxygen. We have about 80% of carbon. This is also an underestimate, so we have to round the whole number up or increase it by 1. 120g x .8 is about 96, then divide by 12g = 8 carbons. Since this is an underestimate, we want it to be a 9.

    We now have C9O9 and the rest would be hydrogen. I am guessing it is C9H12O9.

    The DAT won't be this hard.
     
  4. BeaverLover

    BeaverLover SDN Gold Donor
    Gold Donor Classifieds Approved 2+ Year Member

    Joined:
    Sep 2, 2014
    Messages:
    855
    Likes Received:
    532
    Status:
    Dental Student
    Did ADA list empirical formulas as being possible subject on DAT? Don't remember Chad going over it
     
  5. RuffDay

    2+ Year Member

    Joined:
    Apr 9, 2015
    Messages:
    770
    Likes Received:
    351
    Status:
    Dental Student
    I would say expect it. It is actually probably one of the easiest questions you will encounter on the DAT. I had a question that involves finding the empirical formula when I took the DAT.
     

Share This Page