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 · 35% saltStream 2200 kg/h · 5% saltStream 3x₃ = ? %

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

ṁ1 = 850 kg/hx1 = 35 %ṁ2 = 200 kg/hx2 = 5 %
x3 = %
2.Easy
MixerStream 1550 kg/h · 5% saltStream 2300 kg/h · 30% saltStream 3ṁ₃ = ? kg/h

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

ṁ1 = 550 kg/hx1 = 5 %ṁ2 = 300 kg/hx2 = 30 %
ṁ3 = kg/h
3.Medium
MixerStream 1800 kg/h · 15% sugarStream 2ṁ₂ = ? · 40% 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 = 800 kg/hx1 = 15 %x2 = 40 %x3 = 30 %
ṁ2 = kg/h
4.Medium
MixerStream 1950 kg/h · 45% sugarStream 2ṁ₂ = ? · 10% 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 = 950 kg/hx1 = 45 %x2 = 10 %x3 = 35 %
ṁ2 = kg/h
5.Hard
EvaporatorFeed F1100 kg/h · 6% sugarProduct P60% 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 = 1100 kg/hxF = 6 %xP = 60 %
W = kg/h
6.Hard
EvaporatorFeed F2900 kg/h · 13% saltProduct P35% 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 = 2900 kg/hxF = 13 %xP = 35 %
W = kg/h

Answer key

  1. 1. x3 = 29.29 %
  2. 2. ṁ3 = 850 kg/h
  3. 3. ṁ2 = 1200 kg/h
  4. 4. ṁ2 = 380 kg/h
  5. 5. W = 990 kg/h
  6. 6. W = 1823 kg/h

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