What is Separation: Definition and 475 Discussions

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. O

    Finding separation of bright spots

    Homework Statement A scientist decides to do the double-slit experiment in a vertical tube, with the slits at the top and a viewing screen at the bottom as shown. With red light from a HeNe laser (632 nm) a nice pattern forms on the viewing screen, with the bright spots 1.00 cm apart. Now the...
  2. S

    Method of separation of variables for wave equation

    Homework Statement $$u_{tt} = a^2u_{xx} , 0<x< l , t>0 , $$a is constant $$ u(x,0)=sinx , u_{t} (x,0) = cosx , 0<x< l , t>0 $$ $$ u(0,t)=2t , u(l,t)=t^2 , t>0 $$ Homework Equations The Attempt at a Solution I can solve the eigenvalue problem of X(x), and then solve for T(t), but...
  3. T

    Momentum and Impulse separation question

    Homework Statement 3 equal masses at rest break apart as shown. Find the 3rd velocity Homework Equations http://i168.photobucket.com/albums/u175/kingzer2/Photo2013-04-14073115PM_zps0ee829e4.jpg?t=1365985942 The Attempt at a Solution I really have no idea how to do this :( sorry
  4. A

    Separation of variables to solve Schrodinger equations

    I've found many articles online that explain how to solve the Schrodinger equation for a potential dependent on x, but not for one dependent on t. A couple articles said that you could not use separation of variables to solve the Schrodinger equation with a time dependent potential, but they did...
  5. tony873004

    Work required to increase Earth/Moon separation

    Homework Statement The Moon and Earth have masses of 7.4 × 1022 kg and 6.0 × 1024 kg, respectively, and the distance between their centers is 3.8 × 108 m. The amount of work required to pull them further apart so that their separation increases by a factor of 1.6 is most nearly Homework...
  6. Z

    Special Relativity, simultaneity and spatial separation

    Homework Statement To an observer in frame S, two events are simultaneous and occur 600km apart. What is the time measured by an observer in frame S' who measures their spatial separation to be 1200km? Explain the sign of your answer. Homework Equations Lorentz Transformation t' =...
  7. Z

    Why is the Separation of Variables method valid?

    Why is the "Separation of Variables" method valid? Hey guys, Lately I have been focusing on some question that have annoyed me for some time. One of these questions is: Why is the method of separation of variables valid when solving some PDE? Usually smmetry arguments are presented, and...
  8. A

    What is the final expression for the energy in separation of variables?

    Suppose you have some partiel DE describing a physical system with 2 degrees of freedom (e.g. the SE). If you try separation of variables you get something like: Hg(x)h(y) = Eg(x)h(y) now you can separate this to two equations, but the energy has to go in one of them. Is the final...
  9. Duderonimous

    Solving a differential Eq. by separation of variables

    Homework Statement Find all solutions. Solve explicitly for y. y^{'}=y^{2}-y Homework Equations The Attempt at a Solution Case where y'=0 0=y(y-1) y=0,1 when y(t)=0 Case where y'\neq0 y'=y^{2}-y \frac{1}{y^{2}-y}y'=1 \int\frac{1}{y^{2}-y}y'dt=∫1dt \int\frac{1}{y^{2}-y}dy=t+c Cant...
  10. M

    Coulomb Energy in the KI Molecule: Solving for Separation Distance

    The ionization of potassium is 4.34 eV; the electron affinity of iodine is 3.06 eV. At what separation distance will the KI molecule gain enough Coulomb energy to overcome the energy needed to form the K^+ and I^- ions? I'm looking at the solution to this problem and I'm not understanding how...
  11. D

    Timelike separation: which of these two answers do you prefer?

    Homework Statement This is the problem as stated in my textbook: Prove that for a timelike interval, two events can never be considered to occur simultaneously. I thought about two different ways to go about this; both of these ways make sense to me, but I'm not sure if they both make sense...
  12. F

    Projected Separation and 3D Distance Problem (Code Included)

    Hi all, I've written code that takes J2000 equatorial coordinates for 2 objects and calculates (1) the projected separation of between object 1 and object 2 at the distance of object 1, and the Euclidean (3D) distance between objects 1 and 2. The projected separations should be <= the Euclidean...
  13. C

    Universal Central Observer: Doubling Speed of Light Separation

    If Galaxy A drifts apart from Galaxy B with twice the speed of light then how could a Galaxy C next to Galaxy A drift apart from Galaxy A at a similar speed? edit: PS. Wouldn't that need some kind of "universal central observer" to limit Galaxy A from Galaxy C to not drift apart by more than 2*c?
  14. K

    Understanding Pressure Generated By Flow Separation

    Hi! I'm working on a high Reynold's number model, considering flow over an airfoil with a high angle of attack. I know I want to minimize drag. I'm told that flow separation creates pressure drag---relatively low pressure in the wake of my foil. Q1: Why would flow separation cause lower...
  15. M

    Solving a PDE by Separation of Variables - Troubling Condition

    Homework Statement Hopefully no one will mind me posting this as an image. But here it is in tex: Using separation of variables, find the function u(x,t), defined for 0\leq x\leq 4\pi and t\geq 0, which satisfies the following conditions: \frac{\partial^2 u}{\partial...
  16. J

    PDE Separation of Variables with Nonzero Boundary Conditions

    Homework Statement Solve the diffusion equation: u_{xx}-\alpha^2 u_{t}=0 With the boundary and initial conditions: u(0,t)=u_{0} u(L,t)=u_{L} u(x,0=\phi(x) The Attempt at a Solution I want to solve using separation of variables... I start by assuming a solution of the form...
  17. fluidistic

    Circular membrane, PDE, separation of variables, coefficients.

    Homework Statement I must find the oscillations of a circular membrane (drum-like). 1)With the boundary condition that the membrane is fixed at r=a. 2)That the membrane is free. Homework Equations The wave equation \frac{\partial ^2 u }{\partial t^2 } - c^2 \triangle u =0...
  18. 6

    Laplace Equation Solved by Method of Separation of Variables

    Homework Statement Homework Equations Assume the solution has a form of: The Attempt at a Solution It looks like a sine Fourier series except for the 2c5 term outside of the series, so I'm not sure how to go about solving for the coefficients c5 and c10. Any idea?
  19. S

    Electrostatic Separation of Variables in a Square Pipe

    Homework Statement I'm solving a problem where a conducting pipe with a square cross section is being analyzed to find the potential everywhere in space. The pipe lays along the z-axis, so we're really concerned with the x-y plane. My issue isn't so much the general solution via separation...
  20. ElijahRockers

    Engineering Inductor Circuit, separation of variables

    Homework Statement V_o varies as V(t) = 2000e^(-100t) volts for t > 0 i1(0) = -6A i2(0) = 1A thus i0(0) = 5A Find i0(t) for t > 0. I found Leq = 4H V(t) = L di/dt I separated variables and integrated, got 5e^(-100t) but the software is telling me it's wrong... supposedly the answer is...
  21. M

    Separation using acids and bases

    I am doing a lab this week where the objective is to use acids and bases and a microscale extraction to separate three solids in a mixture. The mixture in question is a mixture of naphthalene, benzoic acid, and ethyl 4-aminobenzoate. It will then be put through a series of solvents and...
  22. J

    Is it Possible to Separate Oxygen from Air Using Centrifugal Force?

    Is it possible to separate out the oxygen from atmospheric air by centrifugal force. I am not asking theoretically but practically. In other words is there any device that will act as a gas centrifuge which can separate air molecules in real time? A continuous process as opposed to a batch...
  23. B

    Analyzing 2D Fin Temperature with Separation of Variables

    Homework Statement We have a 2D fin that has length L (x-axis), and thickness t, (y-axis). The left side has a fixed temperature, the right side is insulated, and the top and bottom surfaces are subject to convection. Find an analytical solution for the temperature at steady state. Homework...
  24. M

    Separation of variables, laplace equation

    Homework Statement Two coaxial pipes(radius a) of the same diameter with a small gap between them are maintained at a potential difference V. By separation of variables and fitting coefficient, guess the potential within the pipe, near the gap. Homework Equations The Attempt...
  25. K

    Solving Phase Change & Spatial Separation with Wavelength & Velocity

    Homework Statement A wave of wavelength 75 cm has velocity 375 m/s. a. What is the spatial separation between two points that are 30° out of phase at a particular time? b. What is the phase change at a particular position for a time change of 0.5 ms? Homework Equations u = λ / T...
  26. E

    Learn About Sine Wave Separation and Sound Processing

    Please forgive me, I don't really know how to properly ask my question, so I'll just do my best. I want to learn how sound is processed. More specifically what math goes into figuring out what individual frequencies are within a single sound signal. Like if I had a recording of say 5 separate...
  27. K

    Separation of variables on 2nd order ode

    Hi all Quick one, if one had an equation y' = x on could simply separate the variables and integrate. Now it the equation y'' = x you would use separation of variables what drives this? Also y'' =0. Is the same as. y''dx =0 dx Why is this legal?Thanks in advance
  28. H

    Bouyancy and liquid separation

    Would it be true to say that boyancy, as in helium rising and liquids of different densities separating, with the densest at the lowest point, is an indication of gravity's natural tendency to attract the most dense mater to its centre point? If so is the Schwarzschild radius a natural...
  29. F

    Separation between lowest energy states

    Could somebody point me in the right direction on how to go about starting this question please? In need of some guidance on where to begin. Homework Statement Calculate the separation between the two lowest energy states for an electron confined in an infinite potential well of width 1nm...
  30. T

    How Do You Calculate Angular Separation of Stars Using Different Coordinates?

    Hi all. I have been looking for a formula that gives me the angular separation of two stars. So far I just found this one :http://www.skythisweek.info/angsep.pdf but it uses the RA and DEC of the 2 stars, and I need to use the hour angle and DEC. Is it the same thing? Do I just replace HA by...
  31. E

    Separation of variables , but for 2nd order

    "separation of variables", but for 2nd order Ok, I know how to separate variables in solving an ODE. I am unable to understand a solution I have for a problem which was the result of reduction of order- we end up with u''*sinx-2u'*cosx=0 so turn this into u''/u'=-2cosx/sinx At this point I...
  32. M

    Separation of Variables, Solutions to Laplace's Eqtns with Boundary Conditions

    Not really a specific problem, but just a general question: Does anyone have any good references (preferably online) for solving E&M problems with this method? I'm using Griffith's Electrodynamics book for my class and I'm trying to get ready for a final. This is the only part I'm having...
  33. R

    Flow Separation of Airfoil in terms of Reynolds Number

    Hi I know that for an airfoil, it's typical to describe stall in terms of angle of attack. I'm wondering, how does Re play a role in flow separation of an airfoil (and for objects in general such as a plate, sphere, or cylinder)? One Wikipedia (http://en.wikipedia.org/wiki/Flow_separation) it...
  34. ElijahRockers

    Solve dy/dx=e^(3x+2y) by separation of variables

    Homework Statement solve dy/dx=e^(3x+2y) by separation of variables The Attempt at a Solution \frac{dy}{dx}=e^{3x+2y} \frac{dy}{dx}=e^{3x}e^{2y} e^{-2y}dy=e^{3x}dx \int e^{-2y}dy=\int e^{3x}dx e^{-2y}=-\frac{2}{3}e^3x + C -2y = ln(-\frac{2}{3}e^{3x}+C)...
  35. T

    Chemistry The average separation between H2O molecules in pure water

    Homework Statement I can't answer to that question, and I don't know how to. I have to calculate the average separation between H2O molecules in pure water. Homework Equations The diameter of the molecule is 0.29 nm I think we can use the bohr equation to resolve it? r = (ε0*h2)...
  36. H

    Separation of variables - Laplace's Equation

    Homework Statement Use separation of variables to find the solution to Laplaces equation satisfying the boundary conditions u(x,0)=0 (0<x<2) u(x,1)=0 (0<x<2) u(0,y)=0 (0<y<1) u(2,y)= asin2πy(0<y<1) The Attempt at a Solution I am able to perform the separation of variables...
  37. G

    Separation of Variables in Spherical Schrodinger Equation

    The normalization condition is: ∫|ψ|^{2}d^{3}r=1 In spherical coordinates: d^{3}r=r^{2}sinθdrdθd\phi Separating variables: ∫|ψ|^{2}r^{2}sinθdrdθd\phi=∫|R|^{2}r^{2}dr∫|Y|^{2}sinθdθd\phi=1 The next step is the part I don't understand. It says: ∫^{∞}_{0}|R|^{2}r^{2}dr=1 and...
  38. V

    Understanding Time Dilation in Special Relativity: Separation and Relative Time

    I think I understand much of SR and some GR, but I'm always stuck when this thought comes to mind.It looks like a stupid proposition and never appears in discussions, but want it cleared up. Consider two objects separated by some distance comparable to the speed of light. Thus each observer...
  39. B

    Separating Variables in Differential Equations: Solving dP/dt = P - P^2

    Homework Statement dP/dt=P-P^2 Homework Equations The Attempt at a Solution I know you can separate this and after i did that and did my partial fractions i got t + C = ln(P) + ln(1-P) but i don't know what to do from here i figure you take the e of both sides at some point...
  40. K

    Finding Separation Point: Pressure Coeff vs Angle Graph

    Hi there, I just wanted to know how to find out where the separation point is on a Pressure Coefficient against Angle Graph ? I did some research and found out something called an adverse pressure gradient what does it mean ? I know that it does promote a separation point so would a separation...
  41. S

    Separation of Variables for ODE

    Homework Statement Solve the following equation by separation of the variables: y' tan-1x - y (1+x2)-1 = 0 Homework Equations The Attempt at a Solution I am not sure if tan-1x stands for arctan x or (tan x)-1. (This has been taken out a book.) Any help on this would be...
  42. S

    Delaying boundary layer transition and flow separation

    Hi all, I am looking to learn more about boundary layer control devices that can delay boundary layer transition (Laminar to Turbulent) and also BL devices that can delay flow separation. I have already found loads of info on Vortex Generators but i am having trouble finding info on things...
  43. E

    Solve this differential equation using separation of variables

    Solve the following first order, ordinary differential equations using separation of variables: dy/dx = y^2 x subject to y=-1 when x=0 the correct answer is: y = -2/x^2 + 2 i cannot seem to get this answer, after i separate the variables and integrate both sides i get: y^2 x^2/2...
  44. Z

    Why isn't there an A in the solution for separation of variables in this PDE?

    Homework Statement Given the partial differential equation: ∂2u/∂x2 = ∂2u/∂t2 , where x[0;L] Use separation of variables to find the solution that satisfies the boundary conditions: ∂u/∂x (x=0) = ∂u/∂x (x=L) = 0 Homework Equations The separation of variables method. The...
  45. T

    Differential Equation by Separation of Variables

    Homework Statement Solve the differential equation: y' + cos(x)y = cos(x) The Attempt at a Solution y' = cos(x)(1 -y) \frac{dy}{1-y} = cos(x) dx -ln|1-y| = sin(x) + C \frac{1}{1-y} = e^{sin(x)} + C 1-y = \frac{1}{e^{sin(x)} + C} y = \frac{-1}{e^{sin(x)} + C} + 1 Have I done this...
  46. P

    How Do You Calculate Average Capacitance of a Variable Separation Capacitor?

    Hi there, I'm trying to calculate the average capacitance of a "variable separation capacitor." Google (and all my textbooks) are not helping me at all. The capacitor has two parallel plates, one of which is hinged at one side. Sort of like this... V Basically I need an expression for the...
  47. T

    Flow separation leads to stalling?

    Why does flow separation give less lift? A separated "suction side" would in my pov give zero pressure (which is the lowest possible). And low pressure on suction side is, of course, beneficial. I think I got it now; as the pressure can not drop further a increase in angle of attack will...
  48. H

    Find the minimum separation between 2 pucks

    Homework Statement Two frictionless pucks are placed on a level surface with an initial distance of 20m. Puck 1 has a mass of 0.8 kg and a charge of + 3x10^-4 C while puck 2 has a mass of 0.4 kg and a charge of +3 x10^-4 C. The initial velocity of puck 1 is 12 m/s [E] and the initial...
  49. A

    Find Wave Crest Separation Near Shore

    Homework Statement I have sinusoidal waves traveling along the surface of the water. I'm given the relation v=\sqrt{gh} where h is the depth of the water. I'm given that when the water is 5 m deep the wavelengt of the waves is 1.4 m. I"m asked how far apart the wave crests are near the...
  50. L

    How Many Tubes Are Required to Achieve a Specific Isotope Concentration?

    Homework Statement Want to separate two isotopes whose atomic masses differ by one neutron mass. We do this by filling a tube of height H with a gaseous mixture of the two isotopes Derive a formula of the enrichment factor [n1 (H)/ n2 (H)]/ [n1(0)/n2(0)] If the gas from the top of the...
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