Separation Definition and 476 Threads

A separation process is a method that converts a mixture or solution of chemical substances into two or more distinct product mixtures. At least one of results of the separation is enriched in one or more of the source mixture's constituents. In some cases, a separation may fully divide the mixture into pure constituents. Separations exploit differences in chemical properties or physical properties (such as size, shape, mass, density, or chemical affinity) between the constituents of a mixture.
Processes are often classified according to the particular differences they use to achieve separation. If no single difference can be used to accomplish the desired separation, multiple operations can often be combined to achieve the desired end.
With a few exceptions, elements or compounds exist in nature in an impure state. Often these raw materials must go through a separation before they can be put to productive use, making separation techniques essential for the modern industrial economy.
The purpose of separation may be analytical, can be used as a lie component in the original mixture without any attempt to save the fractions, or maybe preparative, i.e. to "prepare" fractions or samples of the components that can be saved. The separation can be done on a small scale, effectively a laboratory scale for analytical or preparative purposes, or on a large scale, effectively an industrial scale for preparative purposes, or on some intermediate scale.

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  1. S

    Minimimum separation of to resolve 2 stars

    A telescope has an objective mirror of 6m. An astronomer uses it to determine if a certain object is a binary star, i.e. two stars in orbit around a common point. If the object is 25 light years away (a light year is the distance light travels in one year) what is the minimum separation of...
  2. G

    Finding the Equilibrium Separation in a Diatomic Molecule: A Scientific Approach

    Oh boy...this problem has stumped me. I am not even sure I know where to start: The potential energy of a diatomic molecule (a two-atom system like H2 or O2) is given by U= (A/r^12) - (B/r^6) where r is the separation of the two atoms of the molecule and A and B...
  3. P

    Angular Separation Between Two Stars

    :confused: I aim trying to do a problem where I have 2 Equatorial Coordinates, and I need to find the angular distance in between this two points. Thanks in advance. :confused:
  4. D

    Solving a Physics Problem: Inverted Image & Lens Separation

    I have this Physics Problem which I am not to sure where to start it from. The problem is: A real inverted image I of an object O is formed by a certain lens. The object-image speration is d = 0.40m, measured along the central axis of the lens. The image is just half the size of the...
  5. E

    Radial Velocity, Angular Separation, and Solar Apex: Q&A

    I missed this class the other day and my prof isn't answering his email right now so I thought I'd ask it here. I want the answer to the question, but really I'm looking for the relationship between the values. Q: A star located 135 degrees from the solar apex on the celestial spehe is at...
  6. H

    How Do Separation Axioms Apply to Subspaces?

    How do separation axioms carry over to subspaces? Some are clear -- it's easy to see that if any two points of a space X are separated by neighborhoods, then the same must be true of any subset S of X. But what about the nicer ones? Is it true that if S is a subset of a normal space, that...
  7. G

    Separating Isomers: Efficient Method for Chemists?

    is any other chemist on here familiar with trying to separate isomers? I hate how tedious it is, after I run a silica gel column, I have to take each fraction evaporate the eluent, dissolve what is left behind in methanol, prepare LC/MS sample, and wait 3.2 min for each sample to run in order to...
  8. G

    Calculate separation of galaxies as a function of time

    I'm working on a problem that has me baffled mathematically. What equation can I use to calculate the future distance between two galaxies not gravitationally bound receding at a Hubble constant of 70km/sec/Mpc as a function of time. Stated in another way, if two distant galaxies start off...
  9. L

    Finding Quantitative Proof of Optimal Helmholtz Coil Separation

    I'm trying to track down a quantitative proof that the most uniform magnetic field between two Helmholtz coils occurs for a separation equal to their radii. So far I've just been playing around with the Biot-Savart law and proving that B is identical at several trial points along the axis...
  10. SOS2008

    News Separation of Church and State May God Bless the rest of us?

    Separation of Church and State..."May God Bless"...the rest of us? In the wake of the 2004 election, last count was that the IRS was investigating 60 religious organizations for endorsing Bush from the pulpit. The mixing of religion in politics has become a much more serious problem then most...
  11. C

    Molecular Separation of Water: Energy Needed?

    Could some kind chemistry pro here tell me the energy required for molecular separation of water into H and O2? Thxs. :smile:
  12. S

    How to Calculate the Gradient of a Separation Vector?

    Let c' be the separation vector from a fixed point(x'',y'',z'') to the point (x,y,z) and let c be its length. show that Gradient(1/c) = -c'(hat)/c^2 Thnaks for the help
  13. W

    Is Separation of Variables a Valid Method for Reducing PDEs to ODEs?

    Hi, In physics, many PDEs' equation can be reduced to a number of ODEs' equations by "Separation of Variables". According to my knowledge, "Separation of Variables", it just subsitutes the function, for example F(x,y,z), by a product of three function, X(x)Y(y)Z(z). Why does it work? I mean...
  14. PerennialII

    QM field separation principle

    QM field separation "principle" I came across a term called "QM field separation "principle"" (or theorem, method etc.) and was left thinking, whether this is simply identifiable to general representation of fields (tensor ones typically) as a sum of their symmetric and antimetric components...
  15. wasteofo2

    News Democracy is best served by strict separation of church and state.

    Personally, I believe this firmly, but I'm interested in seeing what some of you people who use "secularist" as a dirty word think of the topic, and how you can defend religious involvement in governmental policy... Paz, Jacob
  16. M

    How a polar solvent works in the separation of polar dyes?

    Explain how a polar solvent works in the separation of polar dyes? How might chromatography be useful in forensic science? i only thing i can think of is figuring out what pen the criminal used... i really need help on this... :rolleyes:
  17. N

    Calculating Amplitude of Brick Separation from Piston with SHM

    A brick is resting atop a piston that is moving vertically with simple harmonic motion of period 1.08 s. At what amplitude will the brick separate from the piston? I came across this question reviewing for my test next Thursday. Anyway, I can calculate the angular frequency using the...
  18. Cyrus

    Separation of Linear and Angular Momentum - Explained

    I was wondering if someone could take the time to explain why linear and angular momentum are two separte things that can never be converted from one form to another. Thanks
  19. G

    The equivalence of observed separation and relativistic velocity.

    The final conversatation between Doc Al and Russ_Watters in post 78 in the Speed of light thread went as: Reading this last post led me to question whether the conversation between Doc Al and Russ_Watters ought not be left unanalyzed. I had finished reading the entire thead earlier and began...
  20. S

    Deriving Electric Field Independence on Negligible Separation

    I read from a website that the electric field is independent of the separation between the plates if the separation is negligibly small. But how to derive this?
  21. C

    Having trouble with differential equations and separation of variables

    two problems in particular, one i got in calc, the other in physics one asks if a = -v and v = 1 when t = 0 what is a possible position function for this equation the other one is given a = 3x and starting at rest from x = 0 find the velocity at 5 seconds i can't seem to...
  22. C

    Internuclear separation between ions in a crystal-

    Okay, I'm hoping someone here can explain this homework qustion I've got bcause we don't seem to have anything in our notes that covers it, so any help would be great- thanks! Potassium fluoride (K+F-) is an ionic crytal having density 2.48x10^3 kg/m^3 Assuming that the diameters of the K+...
  23. J

    Are Points with Separation the Key to Understanding Dimensions?

    I'm getting tired of waiting. I'm not that smart in science, but I have done a couple of very remarkable engineering feats, and I have figured out what happens when points have distance between them. If you look at the screen that comes up between screens on this website, the screen with a...
  24. T

    6 degrees of separation hypothesis: Do you believe it?

    This hypothesis basically states that any 2 people on Earth are connected by no more than six levels of acquaintances.
  25. T

    News Church/State Separation: Pros & Cons

    "In God we Trust" I'm sure that this topic came up before, but i cou;detn find it in the search so... I was just talking to a friend and some how we got on the topic of separation of church and state. We both agreed that it is not seprate and the way poloticians who representg our country...
  26. Z

    News Is Separation of Church and State Still Relevant?

    Discuss... (Hell, at least it isn't another thread about Iraq or Israel!)
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