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 1450 kg/h · 10% NaOHStream 2450 kg/h · 25% NaOHStream 3ṁ₃ = ? kg/h

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

ṁ1 = 450 kg/hx1 = 10 %ṁ2 = 450 kg/hx2 = 25 %
ṁ3 = kg/h
2.Easy
MixerStream 11000 kg/h · 40% sugarStream 2650 kg/h · 5% sugarStream 3x₃ = ? %

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

ṁ1 = 1000 kg/hx1 = 40 %ṁ2 = 650 kg/hx2 = 5 %
x3 = %
3.Medium
MixerStream 1600 kg/h · 5% sugarStream 2ṁ₂ = ? · 30% sugarProduct25% sugar

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

ṁ1 = 600 kg/hx1 = 5 %x2 = 30 %x3 = 25 %
ṁ2 = kg/h
4.Medium
MixerStream 1700 kg/h · 40% saltStream 2ṁ₂ = ? · 20% saltProduct30% salt

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

ṁ1 = 700 kg/hx1 = 40 %x2 = 20 %x3 = 30 %
ṁ2 = kg/h
5.Hard
EvaporatorFeed F500 kg/h · 16% 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 = 500 kg/hxF = 16 %xP = 30 %
W = kg/h
6.Hard
EvaporatorFeed F4100 kg/h · 9% saltProduct PP = ? · 30%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 = 4100 kg/hxF = 9 %xP = 30 %
P = kg/h

Answer key

  1. 1. ṁ3 = 900 kg/h
  2. 2. x3 = 26.21 %
  3. 3. ṁ2 = 2400 kg/h
  4. 4. ṁ2 = 700 kg/h
  5. 5. W = 233.3 kg/h
  6. 6. P = 1230 kg/h

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