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 · 20% sugarStream 2600 kg/h · 10% sugarStream 3x₃ = ? %

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

ṁ1 = 250 kg/hx1 = 20 %ṁ2 = 600 kg/hx2 = 10 %
x3 = %
2.Easy
MixerStream 1650 kg/h · 30% saltStream 2100 kg/h · 20% saltStream 3x₃ = ? %

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

ṁ1 = 650 kg/hx1 = 30 %ṁ2 = 100 kg/hx2 = 20 %
x3 = %
3.Medium
MixerStream 1400 kg/h · 35% sugarStream 2ṁ₂ = ? · 15% sugarProduct25% sugar

How much of stream 2 must be added each hour to stream 1 so that the blended product contains 25% sugar? Find ṁ2.

ṁ1 = 400 kg/hx1 = 35 %x2 = 15 %x3 = 25 %
ṁ2 = kg/h
4.Medium
MixerStream 1650 kg/h · 10% NaOHStream 2ṁ₂ = ? · 50% NaOHProduct40% NaOH

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

ṁ1 = 650 kg/hx1 = 10 %x2 = 50 %x3 = 40 %
ṁ2 = kg/h
5.Hard
EvaporatorFeed F3600 kg/h · 16% 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 = 3600 kg/hxF = 16 %xP = 65 %
P = kg/h
6.Hard
EvaporatorFeed F2000 kg/h · 14% 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 = 2000 kg/hxF = 14 %xP = 45 %
W = kg/h

Answer key

  1. 1. x3 = 12.94 %
  2. 2. x3 = 28.67 %
  3. 3. ṁ2 = 400 kg/h
  4. 4. ṁ2 = 1950 kg/h
  5. 5. P = 886.2 kg/h
  6. 6. W = 1378 kg/h

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