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blackhole123

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About blackhole123

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    Baryon
  • Birthday 07/15/1978
  1. Thanks. Don't worry, I have no intention of letting my grades slip at all. I know that I definitely need to do my research before applying as well. School name isn't everything, and I'd like to find a good mentor to work with.
  2. I am currently a chemistry major in my junior year. I have a 3.95 overall GPA (one B freshman year) and a 4.0 in chemistry. I have been doing undergrad research since the beginning of my sophomore year. Last summer I did an REU (if you don't know, it is a 10 week long research program for undergrads). Hopefully I will be doing another REU or internship this coming summer. I have already taken one graduate level chemistry class and got an A. I have my name in one published paper so far (not first author). I feel like I am doing everything that I can possibly do to bolster my chances for
  3. So I'm degasing a solution in a glovebox. The way we did it is get a rubber septum that can cover the bottle opening. We stuck a needle through the top of it, as well as a glass tube with a porous end. We used the needle to create a vacuum in the bottle by hooking up it up to a pump. The glass tube is submerged in the solution, but is stuck through the rubber to be the only opening into the box. The argon from the glovebox then flows down the glass tube and out the frit at the bottom, degassing the solution. I can't figure out why the gas would be sucked down the tube. Sure there is a vacu
  4. 1) Yes only the last contributed to the excess. 2) So we are right that to get excess permanganate, you subtract excess oxalic acid from the amount of oxalic acid from the 100mL that we added? 3) So the permanganate from the original 50mL minus the excess determined from (2) equals the nitrite? Thanks again.
  5. Potassium permanganate (KMnO4) is used to determine the actual concentration of standard solutions containing the nitrite ion. The permanganate ion reacts with nitrous acid according to the following reaction. 2 MnO4- + 5 HNO2 + 5 H+ = 2Mn2+ + 5 NO3- + 3 H2O Pipet in order 50.00 mL of standard KMnO4 solution, 5 mL concentrated H2SO4 and 50.00 mL of NaNO2 solution into a glass-stoppered flask. Making sure that the pipet tip is submerged below the surface of the permanganate-acid solution while delivering the nitrite stock solution. Shake gently and warm on a hot plate to about 70oC. Dis
  6. I'm a second year chemistry major and I love it, but I had a couple questions that I thought some people here could clear up. A lot of my friends are pharmacy majors. They are going to go to school for 6 years, get a pharm D, and then go out and make $100,000 a year. I'd be a chem major no matter what, but how much does a fresh PhD in chemistry usually make right away if they went into industry? The internet tells me $66,000, is that about right? It just seems like I'm going to have to spend more time dealing with more difficult subject matter and have to write a thesis and everything, an
  7. First of all, I'm an undergrad and am currently do undergrad research. So today I was chatting with the graduate student I am working under and somehow the subject of Harry Potter came up and I mentioned that I am going to see it on Thursday night. She then told me that she never read the books because a church elder told her not to. I was really taken aback. Here is this PhD candidate who I know to be an excellent scientist, not reading a childrens book because their minister told them it was bad. I just don't understand how scientists could be so rational and empirical about everythi
  8. So this is my first semester doing undergraduate research, and I'm very exited about it. We have been doing a certain experiment for a couple months now and the first big hurdle we are facing is getting a pure product. Basically, we are trying to make a substance and then analyze it by XRD. The problem is that we are getting a lot of impurities in the final product. I don't want to go into too much detail, but basically there are two steps: adding NaOH to a substance, and then oxidizing it. So far we have tried doing the reaction under nitrogen, and instead of adding the oxidizing a
  9. =Lets say you titrate a weak acid, HA, with a strong base, NaOH. Now, before the equivalence point, the pH is calculated like a buffer because HA + OH- -> A- + H2O. So you have a mixture of a an acid and its conjugate base. My question is, why doesn't this act like a neutralization reaction like a strong acid and strong base? In order to get OH- you have to dissociate NaOH, so you also have Na+ in solution. Why doesn't the Na+ react with the A- to form a salt like a strong acid and strong base would? I'm also confused about buffers in general. You have an acid and its conjugat
  10. Thanks, I think I see my mistake. I was thinking of "a"'s sign as meaning whether it was accelerating or not, i.e. -9.8 meaning it is decelerating and positive meaning it is accelerating, hence even though I considered down as negative, I had a as +9.8 since it increases acceleration when it is going downward.
  11. Makes sense, and then I apply whether is is positive or negative based on whether it is increasing or decreasing? In these problems what should a be, 9.8 or -9.8? Does that change based on whether it is going up or down? Why don't I just post the whole problem: To test the quality of a tennis ball, you drop it onto the floor from a height of 4.00 m. It rebounds to a height of 2.00 m. If the ball is in contact with the floor for 12.0 ms, what is its average acceleration during that contact? The answer is 1.26x10^3m/s^2 So I got the answer I already posted for descent, 8.85, th
  12. I am using the equation for constant acceleration to find velocity. v^2=v(initial)^2+2a(x-x(initial)) Dropping a rock from 4 meters to the ground. Initial velocity is 0, a=9.8, and displacement is -4. So v^2=2(9.8)(-4), and it SHOULD equal=-8.85m/s (I know this is the correct answer, I already got it right on my homework). The velocity should be negative. But obviously my above answer is impossible because you can't take the square root of a negative. When using these constant acceleration equations I make the sign in the above equation negative if it is going upward, and p
  13. So, I basically blew off the last couple weeks of calc 2 because they dropped the lowest test grade so I could skip the final test. Thus, I missed the last half of infinite series. Will I need to teach it to myself for Calc 3 over the summer? "Geometry and vectors of n-dimensional space; Green's theorem, Gauss theorem, Stokes theorem; multidimensional differentiation and integration; application to 2- and 3-D space." There is the course description.
  14. I was using a .45uM filter on a solution, and while water could pass through it quite easily, air does not pass through at all. If you try to pass air through the filter it is impossible. So, does that mean that water is smaller than all the molecules in air, or is it something else? I would have thought something like O2 would be smaller than H20.
  15. I'm not sure how to say this... Is there difference between the cathode and the anode that is there without the actual substances powering the battery? The positive and negative charges of the different electrodes are because of the spontaneous flow of electrons (in a voltaic cell). But don't you have to connect specific wires to specific parts on a voltmeter for it to record? So, if you are making an electrolytic cell and you connected it, would it spontaneously go until you applied an outside source of electrons to reverse the reaction? In other words, the cathode and the ano
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