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 1850 kg/h · 10% NaOHStream 2350 kg/h · 35% NaOHStream 3ṁ₃ = ? kg/h

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

ṁ1 = 850 kg/hx1 = 10 %ṁ2 = 350 kg/hx2 = 35 %
ṁ3 = kg/h
2.Easy
MixerStream 1600 kg/h · 15% sugarStream 2150 kg/h · 40% sugarStream 3ṁ₃ = ? kg/h

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

ṁ1 = 600 kg/hx1 = 15 %ṁ2 = 150 kg/hx2 = 40 %
ṁ3 = kg/h
3.Medium
MixerStream 1950 kg/h · 15% saltStream 2ṁ₂ = ? · 50% 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 = 15 %x2 = 50 %x3 = 35 %
ṁ2 = kg/h
4.Medium
MixerStream 1800 kg/h · 35% saltStream 2ṁ₂ = ? · 5% saltProduct10% salt

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

ṁ1 = 800 kg/hx1 = 35 %x2 = 5 %x3 = 10 %
ṁ2 = kg/h
5.Hard
EvaporatorFeed F1100 kg/h · 12% saltProduct P45% 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 = 1100 kg/hxF = 12 %xP = 45 %
W = kg/h
6.Hard
EvaporatorFeed F3400 kg/h · 11% 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 = 3400 kg/hxF = 11 %xP = 30 %
W = kg/h

Answer key

  1. 1. ṁ3 = 1200 kg/h
  2. 2. ṁ3 = 750 kg/h
  3. 3. ṁ2 = 1267 kg/h
  4. 4. ṁ2 = 4000 kg/h
  5. 5. W = 806.7 kg/h
  6. 6. W = 2153 kg/h

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