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 1400 kg/h · 10% sugarStream 2500 kg/h · 35% sugarStream 3x₃ = ? %

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

ṁ1 = 400 kg/hx1 = 10 %ṁ2 = 500 kg/hx2 = 35 %
x3 = %
2.Easy
MixerStream 1700 kg/h · 40% NaOHStream 2250 kg/h · 10% NaOHStream 3ṁ₃ = ? kg/h

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

ṁ1 = 700 kg/hx1 = 40 %ṁ2 = 250 kg/hx2 = 10 %
ṁ3 = kg/h
3.Medium
MixerStream 1950 kg/h · 20% NaOHStream 2ṁ₂ = ? · 30% NaOHProduct25% NaOH

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

ṁ1 = 950 kg/hx1 = 20 %x2 = 30 %x3 = 25 %
ṁ2 = kg/h
4.Medium
MixerStream 1850 kg/h · 50% saltStream 2ṁ₂ = ? · 10% saltProduct35% salt

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

ṁ1 = 850 kg/hx1 = 50 %x2 = 10 %x3 = 35 %
ṁ2 = kg/h
5.Hard
EvaporatorFeed F4200 kg/h · 18% saltProduct PP = ? · 45%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 = 4200 kg/hxF = 18 %xP = 45 %
P = kg/h
6.Hard
EvaporatorFeed F700 kg/h · 19% NaOHProduct PP = ? · 45%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 = 700 kg/hxF = 19 %xP = 45 %
P = kg/h

Answer key

  1. 1. x3 = 23.89 %
  2. 2. ṁ3 = 950 kg/h
  3. 3. ṁ2 = 950 kg/h
  4. 4. ṁ2 = 510 kg/h
  5. 5. P = 1680 kg/h
  6. 6. P = 295.6 kg/h

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