Mass balance worksheet with answers

Free printable Mass balance worksheet: 6 problems from easy to exam level, with an answer key. Print it or save it as a PDF.

New worksheetPractise online with hints

For teachers: free to print, copy and use in class. Every new worksheet has new values and its own answer key. A link to ExamProblems on your course page is appreciated.

Name: ____________________   Date: ____________

1.Easy
MixerStream 1250 kg/h · 20% sugarStream 2950 kg/h · 5% sugarStream 3x₃ = ? %

Two sugar solutions are mixed at steady state. Find the mass fraction of sugar in the outlet x3.

ṁ1 = 250 kg/hx1 = 20 %ṁ2 = 950 kg/hx2 = 5 %
x3 = %
2.Easy
MixerStream 1950 kg/h · 20% saltStream 2450 kg/h · 40% saltStream 3x₃ = ? %

Two salt solutions are mixed at steady state. Find the mass fraction of salt in the outlet x3.

ṁ1 = 950 kg/hx1 = 20 %ṁ2 = 450 kg/hx2 = 40 %
x3 = %
3.Medium
MixerStream 1500 kg/h · 40% sugarStream 2ṁ₂ = ? · 5% sugarProduct35% sugar

How much of stream 2 must be added each hour to stream 1 so that the blended product contains 35% sugar? Find ṁ2.

ṁ1 = 500 kg/hx1 = 40 %x2 = 5 %x3 = 35 %
ṁ2 = kg/h
4.Medium
MixerStream 1350 kg/h · 40% NaOHStream 2ṁ₂ = ? · 20% NaOHProduct30% NaOH

How much of stream 2 must be added each hour to stream 1 so that the blended product contains 30% NaOH? Find ṁ2.

ṁ1 = 350 kg/hx1 = 40 %x2 = 20 %x3 = 30 %
ṁ2 = kg/h
5.Hard
EvaporatorFeed F1800 kg/h · 18% NaOHProduct PP = ? · 60%Vapour W (pure water)0% NaOH

An evaporator concentrates a NaOH solution by boiling off pure water. Find the product flow P in kg/h.

F = 1800 kg/hxF = 18 %xP = 60 %
P = kg/h
6.Hard
EvaporatorFeed F900 kg/h · 13% sugarProduct P40% sugarVapour W (pure water)W = ? kg/h

An evaporator concentrates a sugar solution by boiling off pure water. Find the water evaporated W in kg/h.

F = 900 kg/hxF = 13 %xP = 40 %
W = kg/h

Answer key

  1. 1. x3 = 8.125 %
  2. 2. x3 = 26.43 %
  3. 3. ṁ2 = 83.33 kg/h
  4. 4. ṁ2 = 350 kg/h
  5. 5. P = 540 kg/h
  6. 6. W = 607.5 kg/h

Full step-by-step solutions: practise this topic on examproblems.com.