More chemistry related questions.

Discussion in 'Chemistry' started by skaught, Dec 3, 2008.

  1. skaught The field its covered in blood Valued Senior Member

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    4,103
    What makes a hydrogen atom and an oxygen atom combine to create water? How could one separate the two once they are combined?
     
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  3. Bishadi Banned Banned

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    2,745
    energy in the form of em (light)

    Diatomic elements. When they combine they release that energy once catalyzed.

    add wavelength/energy

    see the microwave or magnetron http://www.gallawa.com/microtech/magnetron.html


    can also simply use a stinger in which to place two razor blades about a 1/16" apart and wire each side then plug into most any circuit.

    Point is, to use basic electricity is a waste but to impose a specific wavelength the separation is effecient

    ie.... to covert solar cell energy, transformed to the appropriate 'f' for this, hydrogen could be cooking all day long as fuel from water.

    covert the ICE engines to a natural gas (expansion valve at intact) style system with stainless chamber and exhaust components and you just cured our energy crisis by burning hydrogen produced by the sun. (call congress)

    can also use that ICE to run generators when the sun is not out.

    so the use of hydrogen (3 x btu of gas) can burn and store energy with ease and no one can state it is expensive as to convert standard electricity to xf the efficiency exists but some folk don't want the public to know this.

    my suggestion: Don't believe me, go to the lab and try it!
     
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  5. Forceman May the force be with you Registered Senior Member

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    Stable Reaction of 2H2 + O2.

    Two molecules of hydrogen (2H2) and one molecule of oxygen combine due to the fact that hydrogen has an oxidation number of one and in order to combine with one atom of oxygen, there must be two atoms present from the hydrogen reactant to combine with the one oxygen atom. But there are two atoms of oxygen. That is why a stable molecular formula for water is 2H2O rather than H20. Two atoms of hydrogen combine with one oxygen atom. There are two oxygen atoms. 2 hydrogen per one oxygen. Two molecules to compensate for diatomic nature of oxygen. That gives us a total of four hydrogen atoms and two oxygen atoms. The law of conservation of mass and energy must be taken into place.

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  7. Bishadi Banned Banned

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    2,745

    What is the catalyst?

    What conservation is evidenced?
     
  8. Roman Banned Banned

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    The combining of two hydrogen and one oxygen occurs by the hydrogens and oxygens sharing electrons. Every atom wants to have an outer shell or orbit of eight electrons, and to meet this requirement, they have to steal, give up, or share electrons with other atoms. Hydrogen is an exception, since it needs only two to fill its shell, as it is such a small atom. Oxygen needs to gain two electrons. In this way, oxygen an two hydrogens can share between them four electrons (two from oxygen, and one each from the hydrogens), which gives everyone the needed electrons in their orbits.

    These orbits aren't orbits like the way satellites circle a larger body due to gravity. The orbits are better described as quantum shells, where electrons are simply given a probability of being in any one place at a time.

    Reactions that occur are dependent on not just how many valence electrons are available in the outer most shell, but also on the size of the nucleus of the atom- the mass of neutrons & protons at the center. Larger atoms distribute charge differently, and are clumsier to interact with other atoms. That's why the really chemically active elements are at the top of the periodic table. This trait is termed "electronegativity" or basically how much negative charge due to electrons an atom has. Oxygen and flourine are extremely electronegative due to having small nucleii and a lot of, but not eight, electrons in the outermost valence shell. Electronegativity influences how readily a chemical will react with another. Oxygen will react with just about everything, from wood to metal. Sand is actually burnt earth! It's silica dioxide.

    As for the second question, water and hydrogen can be separated by running electricity through water. Plants also separate water into oxygen and hydrogen to build sugar molecules during photosynthesis.
     
  9. John Connellan Valued Senior Member

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    3,636
    Why is the outer shell always 2 or 8 (usually 8)? This seems to be a fundamental for all atoms. Does quantum physics explain this or did we have a theory even before quantum physics?
     
  10. Trippy ALEA IACTA EST Staff Member

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    As Roman alluded to in his post, electrons exist in shells, or orbitals.
    These shells have a shape, that, in part, reflects their energy.
    The behaviour of electrons in atomic orbitals is governed by a set of quantum numbers.

    The first of these is the principal quantum number, n. The range of values for n is all integers greater than 1. Essentially, n reflects which row of the periodic table the element is found in.

    The second of these is the Azimuthal quantum number, l. The range of values for l is between 0 and n-1 inclusive, this, in essence tells us which orbital, or which block of the periodic table we're looking at. For S block elements (Groups 1&2) n=0, for p block elements n=1 (groups 13-18), for d block elements n=2 (Transition metals), and for f block elements (Actinides and Lanthinides) n=3. An interesting thing about this is this number alslo reflects how many nodal surfaces each orbital has.

    The third of these is the magnetic quantum number, m. Essentially, this tells you how many of each orbital there are (or how many different directions each orbital can point in). The range for m is from -l to l inclusive.

    And fourth, and finally, we have the electron spin of ±½.

    All of these combined with the pauli exclusion principle tell you about the structure of the elements.

    Now, as you may or may not be aware, the Group 18 elements have all shells completely full and are (largely) unreactive because of this, so, let's start off by looking in directly at the group 18 elements.

    For the first row, n=1, l=0, m=0, which when combined with the pauli exclusion principle means that we can only have two electrons for the first Group 18 element, because there's only two possible states, and their with the electrons pointing in opposite directions. In other words, both electrons are in the 1s orbital.

    For the second row, n=2, l=(0,1), m=(-1,0,1).
    This gives us 4 possible orbitals IE: {n=2, l=0, m=0} and {n=2, l=1, m=(-1,0,1)}. Each state is capable of holding two electrons of opposing spin, and so, that is where the 8 electrons come from. So, for the first 10 elements, the electronic configuration is 2,8.

    For the third row, things start to get a little more complicated.
    For the third row we get n=3, l=(0,1,2) and m=(-2,-1,0,1,2).
    At first glance this might appear to give us 18 possible states for the outer most electrons, meaning that we should see the electronic structure of 2,8,18.
    n=3 l=0 m=0
    n=3 l=1 m=-1,0,1
    n=3 l=2 m=-2,-1,0,1,2
    But instead, we only see 2,8,8
    So what gives?

    Well, it turns out that because of the way the energy changes as you go from 1s, to 2s, to 3s to 4s that the 4s orbital is actually lower in energy than the 3d orbital, and so the transition metals are in the 4th row, after calcium, rather than in the third row as would seem to be suggested.

    In essence, the explanation boils down to this:
    Two shows up a lot because electrons occur in pairs, and they occur in pairs of opposing spin, this is because of the pauli exclusion principle.
    8 shows up a lot because each row of the periodic table 'adds' 1 s orbital, and 3 p orbitals, and each of these orbitals can hold a pair of electrons.

    Anyway, I hope that helps answer your question.
     
  11. John Connellan Valued Senior Member

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    3,636
    Complicated, but thanks. Did any chemists have a classical explanation for this behaviour before quantum physics?
     

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