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 1350 kg/h · 35% NaOHStream 2550 kg/h · 5% NaOHStream 3ṁ₃ = ? kg/h

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

ṁ1 = 350 kg/hx1 = 35 %ṁ2 = 550 kg/hx2 = 5 %
ṁ3 = kg/h
2.Easy
MixerStream 1150 kg/h · 15% sugarStream 2600 kg/h · 35% sugarStream 3x₃ = ? %

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

ṁ1 = 150 kg/hx1 = 15 %ṁ2 = 600 kg/hx2 = 35 %
x3 = %
3.Medium
MixerStream 1300 kg/h · 5% NaOHStream 2ṁ₂ = ? · 35% NaOHProduct10% NaOH

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

ṁ1 = 300 kg/hx1 = 5 %x2 = 35 %x3 = 10 %
ṁ2 = kg/h
4.Medium
MixerStream 1550 kg/h · 30% saltStream 2ṁ₂ = ? · 20% saltProduct25% salt

How much of stream 2 must be added each hour to stream 1 so that the blended product contains 25% salt? Find ṁ2.

ṁ1 = 550 kg/hx1 = 30 %x2 = 20 %x3 = 25 %
ṁ2 = kg/h
5.Hard
EvaporatorFeed F2700 kg/h · 16% sugarProduct P45% 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 = 2700 kg/hxF = 16 %xP = 45 %
W = kg/h
6.Hard
EvaporatorFeed F2400 kg/h · 9% NaOHProduct PP = ? · 65%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 = 2400 kg/hxF = 9 %xP = 65 %
P = kg/h

Answer key

  1. 1. ṁ3 = 900 kg/h
  2. 2. x3 = 31 %
  3. 3. ṁ2 = 60 kg/h
  4. 4. ṁ2 = 550 kg/h
  5. 5. W = 1740 kg/h
  6. 6. P = 332.3 kg/h

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