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Bsun

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Posts posted by Bsun

  1. No offense man, but if you are still in Highschool geometry right now(as i read in another of your posts) that stuff is going to probably be outside your comprehension for a while. I'm in calculus 3 and can't even remotely follow what they are talking about doing(a 50 step proof?!?). I think most people will never get to math like that, unless they are physics or math majors.

  2. I have mixed feelings about the FCAT. I took it back when I was in 10th grade and passed it with ease, but I knew of several people who did not pass and had to take the HSCT (we were the last class of students who could graduate with HSCT instead of FCAT). Now, these weren't average remedial students, these were people who had GPA's in the 3.5+ range in the IB program. Personally I don't see how they didn't pass the test, but they didn't.

     

    When I was a junior in HS I left the IB program to do dual enrollment classes at a local community college. Part of this switch meant I had to take a highschool health class with non-IB freshmen. Probably 30% of my time in that health class was spent doing worksheets that "prepped" students for the FCAT. I usually helped the teacher grade the worksheets and was shocked to see that more than 50% of the class was consistently getting EVERY QUESTION WRONG. All of these worksheet questions were very basic (graph analysis, reading comprehension, very basica algebra).

     

    All that being said, I believe that there should be a dual method of graduating. For instance, if you didn't pass the FCAT but had a 3.5 or higher GPA, you would get your diploma. There are people in this world who are never going to be able to pass a standardized test. I don't think it's fair to hold students back based only on a single test, if they are hard workers and have kept a high GPA they should still be able to graduate.

  3. Originally posted by w12talon

    Water definatly contain more than just O2.

     

    If you have a glass of water sitting on the table, it will be slightly acidic, pH <7.

     

    This is because it absorbes CO2 from the air to form Carbonic Acid.

     

    H2O+ CO2 --> H2CO3

     

     

    ;)

     

    Technically speaking, H2CO3 in water soln isn't true Carbonic Acid, but rather hydrated CO2.

  4. Originally posted by mnguyen86

    4)You have 500 ml of a buffer solution of 0.100Mof acetic acid and 0.100 M sodium acetate. Ka = 1.8x10^-5 for acetic acid. Tot his buffer was added 25ml of 0.100 M NaOH. What was the starting pH and the final pH?

     

     

    4). The key to remember here is that the strongest acid in appreciable concentration will always react with the strongest base in appreciable concentration.

     

    In this case you have a very strong base OH, reacting with the strongest acid in appreciable concentration in this solution, which is HAc(acetic acid) in this fashion:

     

    HAc + OH ---> H20 + Ac

     

    This reaction goes (practically speaking) to 100%. OH kills any HAc present and forms a water molecule and acetate ion.

     

    So work out the stoicheometry

    (500*.1 - 25*.1)= mmol HAc

    (500*.1 + 25*.1)= mmol Ac-

     

    Setup your K expression

    K(HAc)= [Ac-]*[H30+] / [HAc]

     

    Should be trivial from this point forward.

  5. Originally posted by greg1917

    we now know that we are dealing with 999810gm of water. since water has a density of 1kg/cubicmetre, that means we can use

     

     

    I believe water has a density of 1gram/centimeter^3. Converting these to SI units gives you:

     

    1kg/ 1000g * 100^3 cm^3/m^3 = 1000kg/m^3 as the density of water. I think you may have gotten the cubicmetre and liter mixed up.

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