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 1600 kg/h · 20% sugarStream 2100 kg/h · 5% sugarStream 3ṁ₃ = ? kg/h

Two sugar solutions are mixed at steady state. Find the outlet flow rate ṁ3.

ṁ1 = 600 kg/hx1 = 20 %ṁ2 = 100 kg/hx2 = 5 %
ṁ3 = kg/h
2.Easy
MixerStream 1250 kg/h · 25% NaOHStream 2250 kg/h · 20% NaOHStream 3ṁ₃ = ? kg/h

Two NaOH solutions are mixed at steady state. Find the outlet flow rate ṁ3.

ṁ1 = 250 kg/hx1 = 25 %ṁ2 = 250 kg/hx2 = 20 %
ṁ3 = kg/h
3.Medium
MixerStream 1900 kg/h · 5% saltStream 2ṁ₂ = ? · 30% saltProduct20% salt

How much of stream 2 must be added each hour to stream 1 so that the blended product contains 20% salt? Find ṁ2.

ṁ1 = 900 kg/hx1 = 5 %x2 = 30 %x3 = 20 %
ṁ2 = kg/h
4.Medium
MixerStream 11000 kg/h · 45% NaOHStream 2ṁ₂ = ? · 15% NaOHProduct40% NaOH

How much of stream 2 must be added each hour to stream 1 so that the blended product contains 40% NaOH? Find ṁ2.

ṁ1 = 1000 kg/hx1 = 45 %x2 = 15 %x3 = 40 %
ṁ2 = kg/h
5.Hard
EvaporatorFeed F3700 kg/h · 13% NaOHProduct P40% NaOHVapour W (pure water)W = ? kg/h

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

F = 3700 kg/hxF = 13 %xP = 40 %
W = kg/h
6.Hard
EvaporatorFeed F2700 kg/h · 12% saltProduct P30% saltVapour W (pure water)W = ? kg/h

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

F = 2700 kg/hxF = 12 %xP = 30 %
W = kg/h

Answer key

  1. 1. ṁ3 = 700 kg/h
  2. 2. ṁ3 = 500 kg/h
  3. 3. ṁ2 = 1350 kg/h
  4. 4. ṁ2 = 200 kg/h
  5. 5. W = 2498 kg/h
  6. 6. W = 1620 kg/h

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