Search results

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    Entropy-increases & decreases

    Basically entropy signifies the number of states a system can be in. This means that when there are more particles in a system that the system can attain more states. So when solid sodium reacts with water to form sodium ions, hydrogen and hydroxide ions the system gains entropy because there...
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    Standard enthaply of reaction

    Look at reaction (3) as two separate phases, first reaction (1) happens in reverse and then reaction (2) happens. This isn't what happens but all the energies involved here are state functions which means that it doesn't matter how you got to that state, the energy is always the same. This way...
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    Iron compound

    Not to my knowledge but when the hydroxide ions make up only a tiny portion of the total amount of anions, the crytal in it's entirety might still be mostly describable as Fe3O4 and thus magnetic.
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    Iron compound

    You can't really say the powder that makes up rust is either pure Fe2O3 or pure FeO or pure Fe3O4. It is a crystal matrix with Fe(II) and Fe(III) in it and hydroxide impurities at the crystal-air interface. The formula which indicates the crystals composition is usualyl that which best describes...
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    What is Eθ?

    It's not a theta, it's a zero with a line thru it. It denotes the electrode potential of something at standard conditions. (pressure, temperature etc.)
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    Have you ever embarassed yourself academically

    A teacher once wrote something along the lines of A ~B on the blackboard. A girl put her hand up and asked "What does that squiggle mean?". She proved quite definately that stupid questions do in fact exist!
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    Problematic Synthesis of Sodium Acetate

    A better idea might be to heat it over a slow fire in a frying pan. This will give the soln. plenty of surface area from which to evaporate. Don't let it boil for too long, you don't want too many crystals forming. When you see crystalformation starting stop heating immedeately and put the hot...
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    Sun block that promotes Vitamin D production

    Vitamin D is most succesfully synthesized in the skin at wavelengths of 270-290nm, which is just outside of the UVA and UVB spectra. A sunblock that uses salicylic acid as the effective ingredient shouldnt block Vit D production.
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    Two easy questions!

    If you go to university to study chemistry you're going to need to be competent at goniometry, calculus, vectors etc. and matrices ;)
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    Acetylation- acetic acid or acetic anhydride

    Have a look at the quantities of both chemicals you used, if that doesn't point you in the right direction post all the numbers here and I'll have a look at them for you.
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    What drives you towards academic success?

    Becoming better at stuff than other people is fun. I like the looks on the faces of people when I tell them I study chemistry. You're only in it for yourself but it can't hurt to share a little ;) And by the way, someone has to be the best at something, chances aren't that great you'll end up...
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    Absolute Zero.

    I believe heat can be extracted letting for instance liquid hydrogen evaporate on the surface of the container. The evaporation is endothermic and will absorb some of the energy from whatever you want to cool. I'm not quite clear on how to cool something with a laser as a laser will add energy...
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    Unclear about the Heisenberg uncertainty principle

    So \Delta A = \sqrt{\int{\psi^* A^2 \psi d\tau} - (\int{\psi^* A \psi d\tau})^2}?
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    Is there any difference between Miscible and Soluble?

    Miscible is said when two liquids can be mixed with eachother. Water and oil are not miscible but water and ethanol are miscible. Soluble is what you call a substance when it can dissolve into a solvent. Both systems entail a change in entropy and as such will cause the exchange of energy with...
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    Unclear about the Heisenberg uncertainty principle

    Hi everybody, I have a slightly noobish question and I've searched for the answer unsuccesfully so I'm posting it here. I'm was reading up on the uncertainty priciple when I ran into two phrases that I don't quite understand. They are <A²> and <A>². Am I too apply this as \int \psi^* A^2 \psi...
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    Calculating pKa

    I also work with "Lehningers priciples of biochemistry" and frankly some of the problems are just a b*tch. Unfortunately the solutions arent always perfect either... Suffice it to say: "you right, book wrong".
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    Help with test for anion in Copper Chloride

    perhaps you ever so slightly hydrated the cupricchloride with the dirty spatula which would be why it turned green. When you added the NaCO_3 to the CuCl_2 you made CuCO_3 Which is black. When you then added the hydrochloric acid you converted the CuCO_3 back to CuCl_2 which is pretty soluble...
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    Photon Problem

    google says: (2.99800 * (10^8)) / (10.68*(10^-6)) = 2.83 × 10^13. you might recognise lightspeed somewhere in this equation just like you might just find the wavelength of the light from the laser...
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    Chemical Equilibrium

    For the reaction aA+bB\rightleftharpoons cC+dD K is calculated by K=\frac{[C]^c[D]^d}{[A]^a[B]^b} The capital letters within the brackets denote the molarities of the reagents in the reaction. The reaction takes place within one system, Does the system change druing the reaction? And in...
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    Prove of refractive index

    According to the definition these triangles áre similar because when you shrink one side the become congruent which is apparently enough to qualify them as "similar" (I have looked this up.). Frankly I thought the explanation was pretty straightforward...
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    Is Science Becoming a Religion?

    I think we are mistaking religion as a possible substitute for science. I think that it is in fact just a theorum. An early an rather crude attempt to explain the world around us. It has since it's creation been overtaken by more realistic and substantiated theories but because of it's lousy...
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    Boiling points

    In short the boiling point of a substance is set by the attraction it applies upon other particles around it. Functional groups might cause the vanderwaals bonds to be tighter because of unevenly spread charge. Mass is important too because the amount of mass a particle has decides how much...
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    Geomagnetic Field Reversal

    Ive looked this up and no link seems to exist. Humanoid life has not been influenced by the last mafnetic reversal for as far as is presently known.
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    PH of weak acid/weak base salts

    The first reaction isn't even correct and frankly I don't know why you think that a strong base like calciumhydroxide would create an acidic particle like H3O^+. This reaction would occur: Ca(H_2O)_6^{2+}(aq)+H_2O(l) \rightleftharpoons CaOH(H_2O)_5^+(aq)+H_3O^+(aq) Which explains why a...
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    Ph meter or acid/base titration?

    The pH meter is accurate but it could be broken or poorly calibrated. Acid/base titration is accurate but painstaking work. Make your pick.
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    Reduction in consumption of fossil fuels

    If you have a lot of cash why don't you just build a few simple wind generators yourself? Darrius mills are simple to make and kind of foolproof :) (They look awsome too :D)
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    I need Helps . Decomposition Reaction WE

    The colour change tells you that the Cu(OH)_2 has changed somehow chemically. Since the most likely change is dehydration that is what you should reasonably assume is what happened. Basically the Cu(OH)_2 was probably hydrated to some extent and what happened is that you have removed this...
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    Geiger counter

    which particle would you call neutral here?
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    Geiger counter

    it attracts them and it might deflect them from the geiger counter. My point was that you first have to look at the differences between the types of radiation and the influence the magnet might have on them.
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    Are physicists religious?

    I've always thought of religions as cruse scientific theories. Simply attempts to explain that which we can not yet explain. It would seem to me that a real objective researcher would not be so lazy to accept the notion of an allmighty one that "just happened to do things this way".