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 1350 kg/h · 25% sugarStream 2650 kg/h · 35% sugarStream 3ṁ₃ = ? kg/h

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

ṁ1 = 350 kg/hx1 = 25 %ṁ2 = 650 kg/hx2 = 35 %
ṁ3 = kg/h
2.Easy
MixerStream 1250 kg/h · 30% saltStream 2150 kg/h · 25% saltStream 3ṁ₃ = ? kg/h

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

ṁ1 = 250 kg/hx1 = 30 %ṁ2 = 150 kg/hx2 = 25 %
ṁ3 = kg/h
3.Medium
MixerStream 11000 kg/h · 45% sugarStream 2ṁ₂ = ? · 15% 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 = 1000 kg/hx1 = 45 %x2 = 15 %x3 = 25 %
ṁ2 = kg/h
4.Medium
MixerStream 1400 kg/h · 40% 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 = 400 kg/hx1 = 40 %x2 = 20 %x3 = 25 %
ṁ2 = kg/h
5.Hard
EvaporatorFeed F600 kg/h · 14% NaOHProduct P35% 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 = 600 kg/hxF = 14 %xP = 35 %
W = kg/h
6.Hard
EvaporatorFeed F700 kg/h · 15% 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 = 700 kg/hxF = 15 %xP = 45 %
P = kg/h

Answer key

  1. 1. ṁ3 = 1000 kg/h
  2. 2. ṁ3 = 400 kg/h
  3. 3. ṁ2 = 2000 kg/h
  4. 4. ṁ2 = 1200 kg/h
  5. 5. W = 360 kg/h
  6. 6. P = 233.3 kg/h

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