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 1350 kg/h · 20% sugarStream 2600 kg/h · 35% sugarStream 3x₃ = ? %

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

ṁ1 = 350 kg/hx1 = 20 %ṁ2 = 600 kg/hx2 = 35 %
x3 = %
2.Easy
MixerStream 1850 kg/h · 5% NaOHStream 2500 kg/h · 30% NaOHStream 3x₃ = ? %

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

ṁ1 = 850 kg/hx1 = 5 %ṁ2 = 500 kg/hx2 = 30 %
x3 = %
3.Medium
MixerStream 1250 kg/h · 50% sugarStream 2ṁ₂ = ? · 15% sugarProduct35% sugar

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

ṁ1 = 250 kg/hx1 = 50 %x2 = 15 %x3 = 35 %
ṁ2 = kg/h
4.Medium
MixerStream 1200 kg/h · 40% sugarStream 2ṁ₂ = ? · 20% 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 = 200 kg/hx1 = 40 %x2 = 20 %x3 = 30 %
ṁ2 = kg/h
5.Hard
EvaporatorFeed F3600 kg/h · 16% sugarProduct P35% 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 = 3600 kg/hxF = 16 %xP = 35 %
W = kg/h
6.Hard
EvaporatorFeed F4700 kg/h · 10% sugarProduct PP = ? · 60%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 = 4700 kg/hxF = 10 %xP = 60 %
P = kg/h

Answer key

  1. 1. x3 = 29.47 %
  2. 2. x3 = 14.26 %
  3. 3. ṁ2 = 187.5 kg/h
  4. 4. ṁ2 = 200 kg/h
  5. 5. W = 1954 kg/h
  6. 6. P = 783.3 kg/h

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