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 1450 kg/h · 25% sugarStream 2150 kg/h · 15% sugarStream 3ṁ₃ = ? kg/h

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

ṁ1 = 450 kg/hx1 = 25 %ṁ2 = 150 kg/hx2 = 15 %
ṁ3 = kg/h
2.Easy
MixerStream 1900 kg/h · 20% NaOHStream 2100 kg/h · 10% NaOHStream 3ṁ₃ = ? kg/h

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

ṁ1 = 900 kg/hx1 = 20 %ṁ2 = 100 kg/hx2 = 10 %
ṁ3 = kg/h
3.Medium
MixerStream 1950 kg/h · 45% saltStream 2ṁ₂ = ? · 20% saltProduct35% salt

How much of stream 2 must be added each hour to stream 1 so that the blended product contains 35% salt? Find ṁ2.

ṁ1 = 950 kg/hx1 = 45 %x2 = 20 %x3 = 35 %
ṁ2 = kg/h
4.Medium
MixerStream 1950 kg/h · 50% saltStream 2ṁ₂ = ? · 5% saltProduct45% salt

How much of stream 2 must be added each hour to stream 1 so that the blended product contains 45% salt? Find ṁ2.

ṁ1 = 950 kg/hx1 = 50 %x2 = 5 %x3 = 45 %
ṁ2 = kg/h
5.Hard
EvaporatorFeed F1600 kg/h · 16% saltProduct P50% saltVapour W (pure water)W = ? kg/h

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

F = 1600 kg/hxF = 16 %xP = 50 %
W = kg/h
6.Hard
EvaporatorFeed F3500 kg/h · 17% 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 = 3500 kg/hxF = 17 %xP = 35 %
P = kg/h

Answer key

  1. 1. ṁ3 = 600 kg/h
  2. 2. ṁ3 = 1000 kg/h
  3. 3. ṁ2 = 633.3 kg/h
  4. 4. ṁ2 = 118.8 kg/h
  5. 5. W = 1088 kg/h
  6. 6. P = 1700 kg/h

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