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 1900 kg/h · 10% saltStream 2500 kg/h · 15% saltStream 3x₃ = ? %

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

ṁ1 = 900 kg/hx1 = 10 %ṁ2 = 500 kg/hx2 = 15 %
x3 = %
2.Easy
MixerStream 1500 kg/h · 5% sugarStream 2450 kg/h · 30% sugarStream 3ṁ₃ = ? kg/h

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

ṁ1 = 500 kg/hx1 = 5 %ṁ2 = 450 kg/hx2 = 30 %
ṁ3 = kg/h
3.Medium
MixerStream 1250 kg/h · 30% sugarStream 2ṁ₂ = ? · 5% 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 = 250 kg/hx1 = 30 %x2 = 5 %x3 = 25 %
ṁ2 = kg/h
4.Medium
MixerStream 1350 kg/h · 30% sugarStream 2ṁ₂ = ? · 10% sugarProduct20% sugar

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

ṁ1 = 350 kg/hx1 = 30 %x2 = 10 %x3 = 20 %
ṁ2 = kg/h
5.Hard
EvaporatorFeed F500 kg/h · 13% NaOHProduct P50% 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 = 500 kg/hxF = 13 %xP = 50 %
W = kg/h
6.Hard
EvaporatorFeed F4000 kg/h · 5% sugarProduct PP = ? · 65%Vapour W (pure water)0% sugar

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

F = 4000 kg/hxF = 5 %xP = 65 %
P = kg/h

Answer key

  1. 1. x3 = 11.79 %
  2. 2. ṁ3 = 950 kg/h
  3. 3. ṁ2 = 62.5 kg/h
  4. 4. ṁ2 = 350 kg/h
  5. 5. W = 370 kg/h
  6. 6. P = 307.7 kg/h

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