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Homework Help: Material balance problem

  1. Oct 4, 2014 #1
    I have an issue with this question:

    An aqueous solution containing 15% NaOH and 0.5% NaCl is concentrated at a rate of 100 kg/min in an evaporator. The concentrated solution is then mixed with 2000 kg of aqueous NaOH solution in a mixer. At the end of one hour a sample is collected from the mixer and analysed. The analysis shows 40% NaOH and 0.8574% NaCl. Calculate:

    1. The concentration of the original solution in the receiver
    2. The composition of the concentrate from the evaporator
    3. The mass of water (in kg) evaporated in one hour.

    When it says that the solution in concentrated at a rate of 100 kg/min, does it mean that the amount entering the evaporator is 100kg in one minute? Or is it the amount leaving the evaporator?

    Can this problem be solved without knowing the composition of the 2000 kg aqueous NaOH entering the mixer?
  2. jcsd
  3. Oct 9, 2014 #2
    Thanks for the post! Sorry you aren't generating responses at the moment. Do you have any further information, come to any new conclusions or is it possible to reword the post?
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