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This is a three-question quiz with a total of seven unknowns that must be solved for. After (optionally) entering your name and then beginning the quiz, you will be given a scenario with two unknown values (see below).

Enter the correct mole fractions and flow rates in the light yellow input boxes. Answers should have a precision of two digits after the decimal place (e.g., 2.15 kmol/h). A correct answer is considered within ±0.01 of the solution. After you have entered your answers in the input boxes, press to display the correct answers. Then, press to proceed to the next question. Once all seven unknowns have been solved for, your score will be displayed. If you entered your name at the beginning of the quiz, your name will be displayed alongside your score so you may screenshot the page and send the image to your instructor. You may attempt the quiz as many times as you like by pressing . Each time you re-attempt the quiz, the unknowns to be solved for will be randomized and the flow rates and mole fractions will be randomized (i.e., the quiz will be different each time you attempt it). To see the equations needed to solve each mass balance, press .

For the first scenario, a binary mixture is fed to a distillation column. Two of the six variables are unknown, and their values are obtained from the mass balances below (where \(F\), \(D\) and \(B\) are the feed, distillate and bottoms flow rates (kmol/h), and \(z_{F}\), \(x_{D}\) and \(x_{B}\) are the feed, distillate and bottoms mass fractions of the more volatile component):

$$ [1] \quad F = D + B $$

$$ [2] \quad z_{F} F = x_{D} D + x_{B} B $$

For the second scenario, a binary mixture is fed to a distillation column in two streams and the two unknowns are obtained from the mass balances below (where \(F_{1}\) and \(F_{2}\) are the flow rates from feed 1 and feed 2, and \(z_{F,1}\) and \(z_{F,2}\) are the mole fractions of the more volatile component in feed 1 and feed 2):

$$ [3] \quad F_{1} + F_{2} = D + B $$

$$ [4] \quad z_{F,1} F_{1} + z_{F,2} F_{2} = x_{D} D + x_{B} B $$

For the third scenario, a ternary mixture is fed to a distillation column in one feed stream. The mass fractions of components A and B are either given or to be solved for. The three unknowns are obtained from the mass balances below (where subscript \(A\) represents component A, and subscript \(B\) represents component B. Component C is solved for by summing each mole fraction to 1, e.g. \(x_{B,A} + x_{B,B} + x_{B,C} = 1\)):

$$ [5] \quad F = D + B $$

$$ [6] \quad z_{F,A} F = x_{D,A} D + x_{B,A} B $$

$$ [7] \quad z_{F,B} F = x_{D,B} D + x_{B,B} B $$

This simulation was created in the Department of Chemical and Biological Engineering, at University of Colorado Boulder for LearnChemE.com by Neil Hendren under the direction of Professor John L. Falconer. Address any questions or comments to learncheme@gmail.com. All of our simulations are open source, and are available on our LearnChemE Github repository.

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