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. J

    Separation of Variables: How to integrate (x+2y)y'=1 y(0)=2?

    Homework Statement Use separation of variables to solve (x+2y)y'=1 y(0)=2Homework Equations u=2y+x >>I did not know how to start this, so i looked at the back of the book and it said to use that substitution y=(u-x)/2, du=2dy+dx, dy=(du-dx)/2 The Attempt at a Solution so i got the following...
  2. P

    Chromatography as a separation techinique

    Homework Statement In detail, explain the theory behind the use of chromatography as a a.)separation technique. b.) identification technique. Homework Equations The Attempt at a Solution I know that chromatography can be used as a separation technique and also indetification...
  3. H

    Separation and Support Theorems for Convex Sets

    Homework Statement Let C be a closed convex subset of Rn. If y is not in C, show x* in C is the closest vector to y in C if and only if (x-y)(x*-y) >= ||x* - y||2 for all x in C. Homework Equations Theorem. Suppose that C is a convex set in Rn and that y is a vextor in Rn that is not in C...
  4. J

    Separation of variables for quantum harmonic oscillator

    a) Show that the Hamiltonian for the quantum harmonic oscillator in 3D is separable, b) calculate the energy levels.----a) If it's separable H = H_x + H_y + H_z, so do I just re-arrange the kinetic and potential terms of the Hamiltonian in this case? that seems kind of trivial, as if I'm...
  5. J

    Minimum separation, impact parameter, and scattering angle

    Homework Statement Alpha particles of kinetic energy 9.6MeV are incident on a silver foil of thickness 7.0 micro meters. For a certain value of the impact parameter, the alpha particles lose exactly half their incident kinetic energy when they reach their minimum separation from the...
  6. A

    Sensitivity of Isotopic Separation Techniques

    Understandably so, certain isotopic separation techniques are going to be sensitive (U-235, U-233, Li-6) because of their relationship to nuclear weapons. Would any other isotopic separation techniques fall under the wing of any regulating agency in the United States (NRC, NNSA, etc.)? For...
  7. K

    Solve Diff. Eq. by Separation of Variables

    Homework Statement Solve the given differential equation by separation of variables. Homework Equations \frac{dy}{dx} = \frac{xy + 2y - x - 2}{xy - 3y + x - 3} The Attempt at a Solution \frac{dy}{dx} = \frac{xy + 2y - x - 2}{xy - 3y + x - 3} = \frac{(x + 2)(y - 1)}{(x - 3)(y + 1)} (x -...
  8. W

    PDE Separation of Variables: Solving utt = uxx with Boundary Conditions

    Homework Statement Solve the problem. utt = uxx 0 < x < 1, t > 0 u(x,0) = x, ut(x,0) = x(1-x), u(0,t) = 0, u(1,t) = 1 Homework Equations The Attempt at a Solution Here is what I have so far but I'm not sure if I am on the right path or not. u(x,t) = X(x)T(t)...
  9. E

    Ordinary Differential Equations: Separation of Variables

    Please have mercy on my non-mathematical mind... I am struggling so hard with Differential Equations. This is my third time to take the class and I still feel like I am walking through the woods at midnight on an extremely dark night. This is the problem that I am working on: dy/dx =...
  10. H

    About Separation of Variables for the Laplace Equation

    Homework Statement This is a try for the solution of Laplace Equation. We have to calculate the potential distribution in a cylinder coordinate. However, there is a step really bring us trouble. Please go to the detail. You can either read it in the related URL, or in my PDF attachment...
  11. E

    Calculating Separation of Car and Truck

    Homework Statement A car and a truck are heading directly toward one another on a straight and narrow street, but they avoid a head-on collision by simultaneously applying their brakes at t=0 . The resulting velocity-versus-time graphs are shown in the figure . What is the separation...
  12. A

    Electrostatic Problem - finding initial separation of two particles

    Homework Statement One particle has a mass of 3.00 \times 10^{-3} kg and a charge of +8.00 \mu C. A second particle has a mass of 6.00 \times 10^{-3} kg and the same charge. The two particles are initially held in place and then released. The particles fly apart, and when the separation...
  13. J

    Consequences of Stalled Vortex Generators on Diffuser Separation

    If I am using vortex generators in an attempt to delay diffuser separation what would the consequence be of the vortex generators stalling? For instance if I set them at and angle of attack to the flow that was past the stall point.
  14. C

    Is Separation of Variables the Key to Solving Linear PDEs in Finance?

    this may seem like a simple question but how does one know that separation of variables for solving linear PDE's will work. What i mean is that it seems to pick out a form of the solution to a given problem (I have heard that linear PDE's have an infinite number of functions of a particular...
  15. J

    Exploring Social Networks: Path Length and Degrees of Separation

    Since I first leaned of the concept of social networks it has fascinated me but I never really studied the topic. It seems to me a huge topic but is not widely studied compared to other areas of mathematics. What better way to study such things as the spread of information, political views...
  16. R

    Double integral variable separation

    \int^{B}______________{A}\int^{\infty}_______________{0}\frac{t^{N-1}x^{s-N-1}dtdx}{e^{t+x}+1} With the restrictions that that B>A, 0<Re(s)<1 and N is a natural number>1. I think t=ab and x=a(1-b) would work, but I'm not sure how to go from there. I don't need to solve the integral; just...
  17. N

    Calculating Flow Separation Point

    Does anyone know of a way to calculate the point at which flow separation occurs?
  18. H

    Partial Differential Equation using separation of variables

    Homework Statement Solve the heat flow problem using the method of separation of variables: Homework Equations PDE:\frac{\partial u}{\partial t}=k\frac{\partial^{2} u}{\partial t^{2}} for 0<x<L, 0<t<\infty BC's:\frac{\partial u}{\partial x}(0,t)=0,\frac{\partial u}{\partial x}(L,t)=0...
  19. M

    Solving second order PDE by separation of variables (getting 2 ODE's)

    Hi all, For my thesis I would like to solve the following second order nonlinear PDE for V(x,\sigma,t): \frac{1}{2}\sigma^2\frac{\partial^2 V}{\partial x^2}+\frac{1}{2}B^2\frac{\partial^2 V}{\partial \sigma^2}+a\frac{\partial V}{\partial \sigma}=0, subject to the following boundary...
  20. H

    Finding Separable Solutions for a Second-Order Partial Differential Equation

    Homework Statement Hi, I don't really understand separation of variables very well, and I was hoping to do get my mind more clear on the following question: (Q) Use separation of variables to find all the separable solutions of the equation: d²y/dt² -c²(d²y/dx²) + w²y = 0 where 'w'...
  21. P

    Finding Slit Separation Using the Double-Slit Apparatus

    Homework Statement The green line of gaseous mercury at 546nm fals on a double-slit apparatus. If the fifth dark fringe is at 0.150 degree from the centerline, what is the slit separaton? Homework Equations d sin (theta) = m* lambda The Attempt at a Solution ok i used the...
  22. J

    Confused about separation of variables for PDE

    So my book says that to solve a PDE by separation of variables, we check the three cases where λ, the separation constant, is equal to 0, -a^2, and a^2. But in this particular problem, instead of substituting λ=0, λ = a^2, λ= -a^2, they substitute the entire coefficient of X, (λ-1)/k =0, (λ-1)/k...
  23. K

    Calculating Mean Free Path & Avg. Separation of Oxygen Molecules

    Homework Statement (a)What is the mean free path for oxygen molecules at 300K and atmospheric pressure (105 Pa) and the average frequency of collisions for a particular molecule? (The diameter of an oxygen molecule is 0.29 nm). (b)What is the mean free path of oxygen molecules at an...
  24. Q

    Stern-Gerlach Separation Distance on Target Film

    I have a question in which we are instructed to find the separation distance between the two impact zones of Sodium atoms on a photographic plate: A magnet of length l= 0.15m and field gradient \nablaB= 9.0T/m over its full length is used in a Stern-Gerlach experiment. If a beam of Sodium...
  25. S

    Separation Energy of Spin 5/2 Particle in B Field 1.35T

    Homework Statement Calculate the separation energy between the lowest and the highest energy state for a spin 5/2 particle with a magnetic moment 0.7 Bohr magnetons in an external magnetic field of 1.35 T Homework Equations delta E = bohr magneton*B*delta magnetic spin OR Equation for...
  26. K

    Why does separation of variables work?

    To solve a separable ODE like this I would simply multiply each side by dx and then integrate both sides. However, I know that it is only notational convenience that allows me to do this, and what's really going on is slightly more complicated. Take this DE for example...
  27. L

    Estimating t Dependency on Proton Separation d

    Homework Statement Knowing that the wave function of the hydrogen atom is proportional to e-r/a0, estimate how t depends on the proton proton separation d. I need just to make a drawing of the integrand and make a reasonal approximation using my intuition (no numerical methods allowed to...
  28. F

    Calculating Angle of Wedge for Fringe Separation

    Homework Statement fringes are observed when a parrallel beam of light of wavelength 500nm is incident perpendiculary onto a wedge-shaped film with an index of refraction of 1.5. What is the angle of the wedge if the fringe separation is 1/3cm? Homework Equations t(x)=xtan(theta)...
  29. P

    Separating Variables: Solving Differential Equations

    Good day, I have to separate the variables of the formula (dy/dx) + 1 = - (y/x) so I can determine the solution of the differential equation. I get: (dy/dx) + 1 = - (y/x) (dy/dx) = - (y/x) - 1 (dy) = (- (y/x) - 1)dx Though I cannot get rid of the y at the side of dx...
  30. quasar987

    Jordan-Brouwer separation theorem

    For those who have the book, in corollary 19.6 page 234 of Bredon, the Jordan-Brouwer separation theorem has just been proven and so we know that if S is homeomorphic to S^(n-1), then S^n\S has two connected components, which are open in S^n and their boundary is S. So we let V be one of the...
  31. I

    Angular separation help here :p

    Homework Statement the question is:calculate angular separation between 1st order red and 1st order violet.data given:theta=22,d=1.20x10^-6 Homework Equations theta=a/D ( is that the 1?) and if it is dn what would the function be hmm tan? (isnt it related to stellar distances) The...
  32. G

    Separation and Potential/Kinetic Energy

    Homework Statement Two protons that are very far apart are hurled straight at each other, each with an initial kinetic energy of 0.19 MeV, where 1 mega electron volt is equal to 1106 (1.610-19) joules. What is the separation of the protons from each other when they momentarily come to a...
  33. R

    Binary Stars: Equal Mass, 350 Million km Separation, 5.4 Earth Years Orbit".

    Suppose that a binary-star system consists of two stars of equal mass. They are observed to be separated by 350 million {\rm km} and take 5.4 Earth years to orbit about a point midway between them. I got 1.1x10^29 as my answer, but it is incorrect. Can anyone help me out?
  34. I

    Electric potential in cylindrical coordinates using separation of variables

    Hi, I am new to the forum. I've encountered a couple problems with separation of variables in cylindrical coordinates. Problem #1: a clindrical surface of radius R is oriented along the z-axis, and is split into two conducting half-cylinders. The potential satisfies the...
  35. A

    What's with this separation of variables business?

    Electromagnetism just got weird. REALLY weird. Everything was going great until we hit this new chapter on separation of variables. I don't remember doing this kind of stuff in my DiffEqs class. Frankly, I'm feeling overwhelmed. I have a midterm at the end of this week, and I feel as though...
  36. S

    Fluid mechanics: Separation surface of a source in a parallel flow (3D)

    Hello, I have the following problem with respect to fluid mechanics: A source of strength Q is in a 3D space and subjected to a parallel flow U along the x-axis. The position of the source is at (xq,yq,zq). This will lead to the following velocity potential in cartesian and cylindrical...
  37. M

    Separation of sediments from alluvial minerals.

    Hello, I am looking for a technique to separate the sediments (Greywacke) which have been deposited on & in some mineral crystals, which are from an alluvial source. I have tried immersing them in ethanol, which has helped a lot but not 100% efficient... as some of the microscopic grains have...
  38. K

    Separation of phosphates, nitrates and nitrites

    Hello If you had an aqueous solution of phosphates, nitrates and nitrites, how could you separate them? Also, if not answered above, how could you separate a solution of just nitrates and nitrites? thank-you for you're time
  39. K

    Solving Charge Separation Homework

    Homework Statement There are six object. First five are the same and carrying charge Q, the last one is uncharged. Let the first object touch with the second one, the uncharged one obtain x unit of charge. What 's the total charge will the last object get if we let the rest four objects...
  40. S

    Why separation of variables? (electrostatics)

    "A sphere of homogeneous linear dielectric material is palcced in an otherwise uniform electric field E. Find the electric field inside the sphere." Griffiths uses separation of variables to solve laplace's equation in the interior of the sphere. I have two questions. (1) How can you try...
  41. D

    News Separation Church & State in Office

    Ideally, should we only allow athiest to hold public office? This way assuring the separation of church and state? (I was going to use the poll option but it doesn't seem to be working).
  42. Cyrus

    News Separation of Church and State

    I was watching Law & Order and I realized a blatant violation of the separation of church and state. (1) When you swear to tell the truth, you put your hand on a bible. (2) When you talk to a preist, they are legally allowed to not repeat what you told them in confession, even if you...
  43. Battlemage!

    Solve a PDE with Separation of Variables

    Homework Statement Solve the 2-D time-independent Schrödinger equation with V (x,y) = 0: Homework Equations -ћ2/2m ( ∂2Ψ(x,y)/∂x2 + ∂2Ψ(x,y)/∂y2 ) = EΨ(x,y) The Attempt at a Solution I started by getting -ћ2/2m to one side: ( ∂2Ψ(x,y)/∂x2 + ∂2Ψ(x,y)/∂y2...
  44. J

    Separation of solid mixture by extraction

    Hi, I have a question about separation of solid mixture by extraction. so how can you tell what reacts with what and which layer contains what? k for example, if you have a mixture of phenol and salicylic acid, first the mixture is dissolved in diethyl ether... then the solution is mixed with...
  45. R

    Calculating Separation Increase: 2000km Space Drop

    There is a spaceship in low-earth orbit, at 2000km above the surface of the earth. There are two balls in the spaceship that are dropped. The balls are 1m apart. How long will it take for their separation to increase to 1.01m? Assume that one ball is at 2000km, and the other is at 2000km+1m...
  46. F

    Separating Mixtures: Does the Order Matter in Physical Methods?

    when separating mixtures using only physical methods, does the order in which you separate them mater? for example, if i had had urea and napthalene in the mixture...both are water soluble...so to take the urea out i first take out the napthalene through sublimitation and then the urea...
  47. A

    How to Get Rid of Natural Logarithms in Separable Differential Equations

    Homework Statement so here's my equation: dy/dx=(xy+3x-y-3)/(xy-2x+4y-8) so what i did first was factor out the right side =(x+1)(y-3)/(x+4)(y-2) then i did a bunch of manipulation to get the ys on one side and the xs on another (i won't write this out right now but if anyone...
  48. N

    Find the initial separation between the particles

    One particle has a mass of 3.00 10-3 kg and a charge of +7.80 µC. A second particle has a mass of 6.00 10-3 kg and the same charge. The two particles are initially held in place and then released. The particles fly apart, and when the separation between them is 0.100 m, the speed of the 3.00...
  49. Ivan Seeking

    News Churches to challenge tax exemption law - separation of church and state

    http://www.cbsnews.com/stories/2008/09/08/politics/animal/main4424757.shtml
  50. K

    What is the new separation between the charges?

    Homework Statement Two positive point charges are held in place, 0.86 m apart. They are then moved so that their electric potential energy doubles. What is the new separation between the charges? Homework Equations kq/r The Attempt at a Solution had PEb=KQaQb/d=2EPEa, then did...
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