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 1100 kg/h · 35% sugarStream 2750 kg/h · 40% sugarStream 3ṁ₃ = ? kg/h

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

ṁ1 = 100 kg/hx1 = 35 %ṁ2 = 750 kg/hx2 = 40 %
ṁ3 = kg/h
2.Easy
MixerStream 1450 kg/h · 5% saltStream 2500 kg/h · 40% saltStream 3ṁ₃ = ? kg/h

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

ṁ1 = 450 kg/hx1 = 5 %ṁ2 = 500 kg/hx2 = 40 %
ṁ3 = kg/h
3.Medium
MixerStream 1550 kg/h · 45% saltStream 2ṁ₂ = ? · 5% saltProduct15% salt

How much of stream 2 must be added each hour to stream 1 so that the blended product contains 15% salt? Find ṁ2.

ṁ1 = 550 kg/hx1 = 45 %x2 = 5 %x3 = 15 %
ṁ2 = kg/h
4.Medium
MixerStream 1750 kg/h · 20% sugarStream 2ṁ₂ = ? · 45% sugarProduct40% sugar

How much of stream 2 must be added each hour to stream 1 so that the blended product contains 40% sugar? Find ṁ2.

ṁ1 = 750 kg/hx1 = 20 %x2 = 45 %x3 = 40 %
ṁ2 = kg/h
5.Hard
EvaporatorFeed F1200 kg/h · 12% NaOHProduct PP = ? · 35%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 = 1200 kg/hxF = 12 %xP = 35 %
P = kg/h
6.Hard
EvaporatorFeed F3500 kg/h · 17% sugarProduct P30% sugarVapour W (pure water)W = ? kg/h

An evaporator concentrates a sugar solution by boiling off pure water. Find the water evaporated W in kg/h.

F = 3500 kg/hxF = 17 %xP = 30 %
W = kg/h

Answer key

  1. 1. ṁ3 = 850 kg/h
  2. 2. ṁ3 = 950 kg/h
  3. 3. ṁ2 = 1650 kg/h
  4. 4. ṁ2 = 3000 kg/h
  5. 5. P = 411.4 kg/h
  6. 6. W = 1517 kg/h

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