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Few questions

  1. Feb 28, 2005 #1
    1) Nonpolar liquids are dangerous? How? What are some harmful nonpolar substances--how is nonpolarity harmful? I mean, why exactly?

    2) Is it true that pure distilled water is harmful to drink? I mean pure, without impurities--just pure H2O; it seems safe, but is it really harmful? What will happen if I drink it?

    3) Are 1.0M NaOH and 1.0M HCl the same distance from a neutral SEVEN on the pH scale?

    4) Does natural selection have an effect on species diversity?

    5) Can glucose be a single-bonded hexagonal carbon chain where each carbon is single bonded with two other carbon (in the ring) and one H and one OH?

    6) Do you guys know any site or sites that list all the hydrocarbon rules/ basic arrangements? I mean, not EVERY hydrocarbon, but just the different "varieties"--among suffixes, for example, what does the -ane, -anone, -etc....well, all the suffixes (even the ones I did not list)?

    7) Is glucose and fructose the same C6H12O6 molecule? Is sucrose C12:H24:O11 or C11:H24:O12...

    8) Why can oxygen only have one double bond or two single bonds?

    9) What makes molecules right-handed or left-handed? What would change in molecular properties between different-handed molecules?

    10) Sometimes fibers, i think, are added to ceramics to reduce brittleness/increase flexibility. Would that lower that particular ceramic's melting point?

    11) About the triple point in phase diagrams: now I mean, theoritically, it is one specific temperature, right? But in reality---i mean, is it only one specific temperature? I mean, even if I differ by even a "sextillionth" of a degree/mmHg, we will not have three phases at all...only one/two at all at point? (maybe more water than ice, or more ice that vapor..but still, three? or only one/two?) (Would the substance really notice)

    12) The curves on phase diagrams, between s/l/gas states....they're not solid lines, are they? I mean, same as above, but the same sextillionth difference in pressure/temperature---will the substance really notice?

    13) Just to be sure, the curves on phase diagrams are EMPIRICALLY drawn...from Experimental Data, right? (best-fit lines?)

    14) Now zero quanta (Plank's constant of energy levels) cannot exist, right? I mean, we cannot have "zero" energy, can we?

    15) Now in net ionic equations of aqueous solutions, calcium hydroxide is considered soluble, right? In that case, wouldn't hydroxides of magnesium and beryllium ALSO be soluble as well?

    16) Well, a slight allusion towards relativity theory, theory of relativity-------what is the GAS CONSTANT relative to????

    17) Why must pressure be applied to freeze helium in addition to lowering temperature, rather than JUST lowering temperature to very low levels, as for the heavier noble gases?

    18) Why do chromium and copper have irregular orbital descriptions?

    19) What math and/or physics must I understand prior to understanding Schrodinger's wave function/equation---i.e., the exact equation and its precise reasoning?

    20) Although H3PO4 is not considered a "Strong" acid (HCl, HNO3, H2SO4, HClO4), would 1.0M H3PO4 still be harmful/cause harm/tissue damage?

    21) Well, now that I think about, HF could be hydroflouric acid, right?
     
  2. jcsd
  3. Feb 28, 2005 #2

    dextercioby

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    21)Yes,HF is hydrofluoric acid.
    20)I frankly doubt it.
    19)Classical mechanics and lots of linear algebra,complex analysis and functional analysis.
    18) Check Hund's rules and how they help build the electronic structure of elements.

    Daniel.
     
  4. Feb 28, 2005 #3
    Would HF hydroflouric acid be harmful?
     
  5. Feb 28, 2005 #4
    I think it has comething to do with the bones. It reacts with it to form calcium flouride, which blocks your blood vessels.

    Thats what i heard :rolleyes: But someone do correct me if im right or wrong with this..
     
  6. Mar 2, 2005 #5
    Btw, will all gases liquefy prior to achieving absolute zero??
    and
    who'll answer the few remaining questions in my thread?
     
  7. Mar 3, 2005 #6

    Gokul43201

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    I will answer them if you will give your assurance that they are not homework. Many of the questions do not sound like homework - and are very good questions too - but some surely look like textbook problems.
     
  8. Mar 3, 2005 #7
    They're not homework problems; just a couple of curiousities i've had :smile:
    (As for textbook problems''', I'm not sure_; I haven't scanned the textbook for that)
    (i love question #16)
    also, question #4 is not really chemistry--but i'm wondering though: natural selection will favor a more "fit" species, but would that imply lower genetic diversity among the organisms under consideration? I think it has no effect, but does it?
     
    Last edited: Mar 3, 2005
  9. Mar 4, 2005 #8

    ShawnD

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    What you say is bold. What I say isn't bold.

     
    Last edited: Mar 4, 2005
  10. Mar 4, 2005 #9
    It is a precise temperature AND pressure. If you added or removed a small amount of heat or changed the pressure slightly, then the equilibrium would be shifted, but there would still be three phases, and the temperature and pressure would still be the same

    When a substance undergoes a phase transition, the temperature remains constant until there is a complete transformation of the substance from one state to the other. You notice this when you do distillation - the vapor temperature will rise very rapidly - then stop at a specfic temperature until all of one substance has boiled away, then start rising again.

    For the most part yes, but there are models which produce good approximations, such as the Clausius-Clayperon equation for vapor pressure of a liquid.

    No, a particle cannot possess zero energy. If it did, we would know its possition with 100% certainy, which
    violates the Heisenberg uncertainty principle.

    Calcium hydroxide is only slightly soluble. Beryllium and Magnesium have higher ionization energies, and thus do not dissolve as well. This is because their valence electrons are closer to the nucleus, and their s orbital is filled, which makes a stable 'duet' . On a related note, beryllium and magnesium metal do not react with the hydroxide in water do not react in water without the prescence of a catalyst, while the group I and rest of the group II elements do.


    I'm not sure what you mean by that. Do you mean would the gas constant change for someone who travelling at some speed relative to the gas?

    Liquid helium behaves very strangely and I'm not sure there is a simple answer - but I suspect helium would be the most likely canidate of any of the noble gases to require pressure as well as lower pressure since its electrons are very close to the nucleus, and the forces present that cause a substance to remain in a liquid phase
    (London dispersion forces) would be alot less.

    The energy levels for a given element are unque - the energy level of the 1s orbital in one element is different from the 1s another element. This is because as you add more electrons, they repel each other and change the allowed energy levels. As you increase the atomic number, the formula for the allowed energy levels gets more and more ugly - and even then its only an approximation because the wave equation has no closed form solution past n = 1. More over, the difference in energy between levels gets smaller and smaller. For chromium and copper, it just so happens that when you add an additional electron, it changes the energy level of all the electrons in a counter intuitive way. There are other exceptions to Hund's rule as well (e.g Cerium and Praseodymium (atomic numbers 58 and 59, respectively))
     
    Last edited: Mar 4, 2005
  11. Mar 4, 2005 #10

    Borek

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    For all practical purposes you are right. But if you want to be exact - no. Hydrochloric acid is much stronger (in terms of dissociation constant) that NaOH. To calculate exact values of pH of 1M solutions you have to use dissociation constants and the distance from the neutral pH will be not the same.

    Take a look at http://www.chembuddy.com/index.php?left$=FAQ (third question). Also you may try BATE for these pH calculations:

    1M HCl pH = 0.00
    1M NaOH pH = 13.73


    Chemical calculators for labs and education
    BATE - pH calculations, titration curves, hydrolisis
     
  12. Mar 4, 2005 #11

    DocToxyn

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    ShawnD, Check out this thread and see if you agree with its conclusions.
     
  13. Mar 4, 2005 #12

    DocToxyn

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    In addition to the ability of HF to cause severe burns, the liberated fluoride ion will scavenge all available calcium. In the long term this would have an effect on bone, but following sufficient exposure, you would die of ventricular fibrillation long before that due to calcium's role in nerve conduction and muscle contraction. Check this link for HF toxicity papers/reports.
     
  14. Mar 4, 2005 #13

    ShawnD

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    I still call BS on the theory.
    I've been drinking distilled water for 19 years and I'm as healthy as they come. Don't try to tell me my distilled water is impure because I checked the resistance in grade 10 to find that it really doesn't conduct electricity any better than normal air does.
     
  15. Mar 5, 2005 #14

    Gokul43201

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    1) Nonpolar liquids are dangerous? How? What are some harmful nonpolar substances--how is nonpolarity harmful? I mean, why exactly?

    ShawnD's got this mostly covered. I'd like to add one little bit. If there's a bucketfull of unknown (possibly poisonous liquid) sitting around, I'd be more careful about going near it if I was told that it's nonpolar. Why ? Because nonpolar liquids tend to have lower boiling points or higher vapor pressures, and I want to minimize the risk of inhaling noxious vapors.

    2) Is it true that pure distilled water is harmful to drink? I mean pure, without impurities--just pure H2O; it seems safe, but is it really harmful? What will happen if I drink it?

    There MAY be some long term effects from drinking deionized water; much less from distilled water. There have been at least 2 different threads discussing this matter here in PF.

    3) Are 1.0M NaOH and 1.0M HCl the same distance from a neutral SEVEN on the pH scale?

    Covered by Borek. x molar HCl will always have a slightly smaller value of pH than x molar NaOH's pOH value - because HCl has a higher dissociation constant. The difference, however gets smaller and smaller, the greater you make the concentrations. A more interesting question here might be : "What's the pH of 1.1M HCl ?"

    4) Does natural selection have an effect on species diversity?

    I'm almost positive it does. But I will not venture any further, for my ignorance in this field is quite extensive.

    5) Can glucose be a single-bonded hexagonal carbon chain where each carbon is single bonded with two other carbon (in the ring) and one H and one OH?

    You can have a "single-bonded hexagonal carbon chain where each carbon is single bonded with two other carbon (in the ring) and one H and one OH". Only, you wouldn't call that glucose. It would be a cyclohexanol.

    Glucose is the name of a specific compound whose anhydrous structure is an aldol. In aqueous solution, it adopts the hemiacetal structure.


    6) Do you guys know any site or sites that list all the hydrocarbon rules/ basic arrangements? I mean, not EVERY hydrocarbon, but just the different "varieties"--among suffixes, for example, what does the -ane, -anone, -etc....well, all the suffixes (even the ones I did not list)?

    Google "IUPAC Nomenclature"
    http://www.chem.qmul.ac.uk/iupac/class/
    http://www.acdlabs.com/iupac/nomenclature/


    7) Is glucose and fructose the same C6H12O6 molecule? Is sucrose C12:H24:O11 or C11:H24:O12...

    8) Why can oxygen only have one double bond or two single bonds?

    Explained in detail by ShawnD. Summary : O has 6 valence electrons and needs 8 for an octet, so it must share 2 of its electrons with 2 "external" electrons to get this octet. This can be achieved through either 2 single bonds or one double bond, but no other way.
     
  16. Mar 5, 2005 #15

    ShawnD

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    I think more nonpolar stuff also soaks into the brain a little faster/longer. The chemical difference between amphetamine and methamphetamine is just a methyl group to make it less polar, but that less polar methamphetamine is significantly more potent.
     
  17. Mar 7, 2005 #16

    Gokul43201

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    9) What makes molecules right-handed or left-handed? What would change in molecular properties between different-handed molecules?

    Google "chirality" - this is too big a topic to describe briefly, and without pictures. Any geometry dependent property changes with changing chirality. Particularly important are reactions such as the binding of enzymes to substrates.

    10) Sometimes fibers, i think, are added to ceramics to reduce brittleness/increase flexibility. Would that lower that particular ceramic's melting point?

    When you make a composite, you no longer have a single melting point. Often, each component melts at its own melting point. Sometimes, depending on factors like the size/distribution of the dispersed particles, you have a range of melting temperatures. In general. The effect on melting point is very case sensitive, but if you are worrying about the likelihood of damage to the composite at temperatures just below the mp of the ceramic, you are justified in that.

    11) About the triple point in phase diagrams: now I mean, theoritically, it is one specific temperature, right? But in reality---i mean, is it only one specific temperature? I mean, even if I differ by even a "sextillionth" of a degree/mmHg, we will not have three phases at all...only one/two at all at point? (maybe more water than ice, or more ice that vapor..but still, three? or only one/two?) (Would the substance really notice)

    In reality, you can be slightly off of a triple point and still see all three phases - thanks to thermal and pressure fluctuations, and the time constant for phase change - which, particularly in solids can be quite large.

    12) The curves on phase diagrams, between s/l/gas states....they're not solid lines, are they? I mean, same as above, but the same sextillionth difference in pressure/temperature---will the substance really notice?

    There are two kinds of phase transitions to distinguish between, here : (i) first order transitions (like the melting of a pure substance), and (ii) higher order transitions (lambda points). Only first order phase transitions (which insludes all common melting and boiling transitions) are represented by curves on a phase diagram. Higher order transitions occupy regions.

    Even in the case of first order transitions, the "substance will not notice" if the difference in temperature is smaller than the size of thermal fluctuations. Remember, temperature (and pressure) is a macroscopic property that represents a statistical average.

    13) Just to be sure, the curves on phase diagrams are EMPIRICALLY drawn...from Experimental Data, right? (best-fit lines?)

    Yes, they are empirically drawn - usually from things known as CCCs (Continuous Cooling Curves) which are generated by experiment. Sometimes, theoretical corrections may be employed to account for some non-equilibrium condition imposed by the measurement system.

    14) Now zero quanta (Plank's constant of energy levels) cannot exist, right? I mean, we cannot have "zero" energy, can we?

    This question is vague. If you have a more specific question/context perhaps...
    For now, you can have "zero quanta", but probably not in the kinds of cases you may have in mind.

    15) Now in net ionic equations of aqueous solutions, calcium hydroxide is considered soluble, right? In that case, wouldn't hydroxides of magnesium and beryllium ALSO be soluble as well?

    Why should they ? Are Mg(OH)2 and Be(OH)2 more ionic than Ca(OH)2 ?

    16) Well, a slight allusion towards relativity theory, theory of relativity-------what is the GAS CONSTANT relative to????

    What is this question relative to????

    17) Why must pressure be applied to freeze helium in addition to lowering temperature, rather than JUST lowering temperature to very low levels, as for the heavier noble gases?

    Pressure must be applied to freeze many fluids. Not all substances are solid at 0K and 0 atm. The choice of 10^5 Pa (1 atm) is an arbitrary number determined by the nature of our atmosphere.

    Helium is a weakly interacting gas (I believe the 2-particle interaction is significantly smaller than those of other noble gases) and hence is liquid down to 0K at pressures up to a few atm. In addition, He4 is a bosonic atom and obeys the rules of Bose Statistics; which makes for surprising behavior at low temperatures. Recently, interesting experiments done at Penn State University (Moses Chan & E Kim, Nature 427 225, 2004) have suggested that solid He4 exhibits a property known as superfluidity...exciting stuff !!
     
    Last edited: Mar 8, 2005
  18. Mar 8, 2005 #17

    Gokul43201

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    18) Why do chromium and copper have irregular orbital descriptions?

    Since Cr has z=24, one would expect it to have the config : [Ar] 4s2 3d4. Yet it prefers to exist as [Ar] 4s1 3d5 (the second 4s electron prefers to live in the 3d subshell instead). This is because half-filled subshells have "extra stability" making them nearly as favorable as fully filled subshells. Comparing the two above configurations, it is found that there is a greater reduction in energy going from 3d4 to 3d5 than there is in going from 4s1 to 4s2.

    A similar argument works for Cu (z=29). You might naturally want to write the config as [Ar] 4s2 3d9, but from a similar argument as above, it is preferable for Cu to be in the state [Ar] 4s1 3d10.

    19) What math and/or physics must I understand prior to understanding Schrodinger's wave function/equation---i.e., the exact equation and its precise reasoning?

    Covered by Dexter

    20) Although H3PO4 is not considered a "Strong" acid (HCl, HNO3, H2SO4, HClO4), would 1.0M H3PO4 still be harmful/cause harm/tissue damage?

    While phosphoric acid is not as dangerous as acids like HCl or HNO3, it is still a pretty scary creature, and all the standard safety precautions must be used while handling (look up "phosphoric msds") it. It is very corrosive to the mucous membrane and parts of the respiratory system, but its vapor pressure is much lower than HCl or H2SO4, so good ventilation will mitigate the effect of vapors.

    21) Well, now that I think about, HF could be hydroflouric acid, right?
    Yes, but it's spelled 'hydrofluoric'.
     
  19. Mar 8, 2005 #18
    1) Benzene is carcinogenic
     
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