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 1250 kg/h · 35% NaOHStream 2650 kg/h · 40% NaOHStream 3ṁ₃ = ? kg/h

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

ṁ1 = 250 kg/hx1 = 35 %ṁ2 = 650 kg/hx2 = 40 %
ṁ3 = kg/h
2.Easy
MixerStream 1900 kg/h · 5% sugarStream 2650 kg/h · 35% sugarStream 3ṁ₃ = ? kg/h

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

ṁ1 = 900 kg/hx1 = 5 %ṁ2 = 650 kg/hx2 = 35 %
ṁ3 = kg/h
3.Medium
MixerStream 1550 kg/h · 30% sugarStream 2ṁ₂ = ? · 5% sugarProduct10% sugar

How much of stream 2 must be added each hour to stream 1 so that the blended product contains 10% sugar? Find ṁ2.

ṁ1 = 550 kg/hx1 = 30 %x2 = 5 %x3 = 10 %
ṁ2 = kg/h
4.Medium
MixerStream 1200 kg/h · 5% NaOHStream 2ṁ₂ = ? · 35% NaOHProduct20% NaOH

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

ṁ1 = 200 kg/hx1 = 5 %x2 = 35 %x3 = 20 %
ṁ2 = kg/h
5.Hard
EvaporatorFeed F2700 kg/h · 5% sugarProduct P50% 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 = 2700 kg/hxF = 5 %xP = 50 %
W = kg/h
6.Hard
EvaporatorFeed F1800 kg/h · 18% 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 = 1800 kg/hxF = 18 %xP = 35 %
P = kg/h

Answer key

  1. 1. ṁ3 = 900 kg/h
  2. 2. ṁ3 = 1550 kg/h
  3. 3. ṁ2 = 2200 kg/h
  4. 4. ṁ2 = 200 kg/h
  5. 5. W = 2430 kg/h
  6. 6. P = 925.7 kg/h

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