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 1700 kg/h · 15% NaOHStream 2750 kg/h · 30% NaOHStream 3ṁ₃ = ? kg/h

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

ṁ1 = 700 kg/hx1 = 15 %ṁ2 = 750 kg/hx2 = 30 %
ṁ3 = kg/h
2.Easy
MixerStream 1900 kg/h · 5% sugarStream 2900 kg/h · 15% sugarStream 3ṁ₃ = ? kg/h

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

ṁ1 = 900 kg/hx1 = 5 %ṁ2 = 900 kg/hx2 = 15 %
ṁ3 = kg/h
3.Medium
MixerStream 1700 kg/h · 10% NaOHStream 2ṁ₂ = ? · 35% 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 = 700 kg/hx1 = 10 %x2 = 35 %x3 = 30 %
ṁ2 = kg/h
4.Medium
MixerStream 1250 kg/h · 30% saltStream 2ṁ₂ = ? · 5% saltProduct10% salt

How much of stream 2 must be added each hour to stream 1 so that the blended product contains 10% salt? Find ṁ2.

ṁ1 = 250 kg/hx1 = 30 %x2 = 5 %x3 = 10 %
ṁ2 = kg/h
5.Hard
EvaporatorFeed F4300 kg/h · 15% saltProduct PP = ? · 55%Vapour W (pure water)0% salt

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

F = 4300 kg/hxF = 15 %xP = 55 %
P = kg/h
6.Hard
EvaporatorFeed F3900 kg/h · 7% sugarProduct P35% 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 = 3900 kg/hxF = 7 %xP = 35 %
W = kg/h

Answer key

  1. 1. ṁ3 = 1450 kg/h
  2. 2. ṁ3 = 1800 kg/h
  3. 3. ṁ2 = 2800 kg/h
  4. 4. ṁ2 = 1000 kg/h
  5. 5. P = 1173 kg/h
  6. 6. W = 3120 kg/h

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