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.

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1.Easy
MixerStream 1550 kg/h · 15% sugarStream 2600 kg/h · 10% sugarStream 3ṁ₃ = ? kg/h

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

ṁ1 = 550 kg/hx1 = 15 %ṁ2 = 600 kg/hx2 = 10 %
ṁ3 = kg/h
2.Easy
MixerStream 1350 kg/h · 5% saltStream 2650 kg/h · 35% saltStream 3ṁ₃ = ? kg/h

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

ṁ1 = 350 kg/hx1 = 5 %ṁ2 = 650 kg/hx2 = 35 %
ṁ3 = kg/h
3.Medium
MixerStream 1750 kg/h · 50% saltStream 2ṁ₂ = ? · 5% saltProduct20% salt

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

ṁ1 = 750 kg/hx1 = 50 %x2 = 5 %x3 = 20 %
ṁ2 = kg/h
4.Medium
MixerStream 1550 kg/h · 35% saltStream 2ṁ₂ = ? · 10% 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 = 35 %x2 = 10 %x3 = 25 %
ṁ2 = kg/h
5.Hard
EvaporatorFeed F1000 kg/h · 14% NaOHProduct PP = ? · 50%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 = 1000 kg/hxF = 14 %xP = 50 %
P = kg/h
6.Hard
EvaporatorFeed F4100 kg/h · 20% sugarProduct PP = ? · 35%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 = 4100 kg/hxF = 20 %xP = 35 %
P = kg/h

Answer key

  1. 1. ṁ3 = 1150 kg/h
  2. 2. ṁ3 = 1000 kg/h
  3. 3. ṁ2 = 1500 kg/h
  4. 4. ṁ2 = 366.7 kg/h
  5. 5. P = 280 kg/h
  6. 6. P = 2343 kg/h

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