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 1900 kg/h · 25% saltStream 2950 kg/h · 15% saltStream 3ṁ₃ = ? kg/h

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

ṁ1 = 900 kg/hx1 = 25 %ṁ2 = 950 kg/hx2 = 15 %
ṁ3 = kg/h
2.Easy
MixerStream 1500 kg/h · 20% sugarStream 2350 kg/h · 30% sugarStream 3x₃ = ? %

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

ṁ1 = 500 kg/hx1 = 20 %ṁ2 = 350 kg/hx2 = 30 %
x3 = %
3.Medium
MixerStream 11000 kg/h · 45% sugarStream 2ṁ₂ = ? · 10% 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 = 1000 kg/hx1 = 45 %x2 = 10 %x3 = 40 %
ṁ2 = kg/h
4.Medium
MixerStream 1300 kg/h · 35% sugarStream 2ṁ₂ = ? · 10% sugarProduct30% sugar

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

ṁ1 = 300 kg/hx1 = 35 %x2 = 10 %x3 = 30 %
ṁ2 = kg/h
5.Hard
EvaporatorFeed F4100 kg/h · 17% 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 = 4100 kg/hxF = 17 %xP = 65 %
P = kg/h
6.Hard
EvaporatorFeed F1100 kg/h · 19% NaOHProduct PP = ? · 60%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 = 1100 kg/hxF = 19 %xP = 60 %
P = kg/h

Answer key

  1. 1. ṁ3 = 1850 kg/h
  2. 2. x3 = 24.12 %
  3. 3. ṁ2 = 166.7 kg/h
  4. 4. ṁ2 = 75 kg/h
  5. 5. P = 1072 kg/h
  6. 6. P = 348.3 kg/h

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