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 1550 kg/h · 35% NaOHStream 21000 kg/h · 5% NaOHStream 3ṁ₃ = ? kg/h

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

ṁ1 = 550 kg/hx1 = 35 %ṁ2 = 1000 kg/hx2 = 5 %
ṁ3 = kg/h
2.Easy
MixerStream 1950 kg/h · 25% sugarStream 2800 kg/h · 10% sugarStream 3x₃ = ? %

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

ṁ1 = 950 kg/hx1 = 25 %ṁ2 = 800 kg/hx2 = 10 %
x3 = %
3.Medium
MixerStream 1800 kg/h · 40% NaOHStream 2ṁ₂ = ? · 20% NaOHProduct30% NaOH

How much of stream 2 must be added each hour to stream 1 so that the blended product contains 30% NaOH? Find ṁ2.

ṁ1 = 800 kg/hx1 = 40 %x2 = 20 %x3 = 30 %
ṁ2 = kg/h
4.Medium
MixerStream 1950 kg/h · 15% NaOHStream 2ṁ₂ = ? · 40% NaOHProduct25% NaOH

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

ṁ1 = 950 kg/hx1 = 15 %x2 = 40 %x3 = 25 %
ṁ2 = kg/h
5.Hard
EvaporatorFeed F3400 kg/h · 19% saltProduct PP = ? · 55%Vapour W (pure water)0% salt

An evaporator concentrates a salt solution by boiling off pure water. Find the product flow P in kg/h.

F = 3400 kg/hxF = 19 %xP = 55 %
P = kg/h
6.Hard
EvaporatorFeed F4600 kg/h · 17% NaOHProduct PP = ? · 40%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 = 4600 kg/hxF = 17 %xP = 40 %
P = kg/h

Answer key

  1. 1. ṁ3 = 1550 kg/h
  2. 2. x3 = 18.14 %
  3. 3. ṁ2 = 800 kg/h
  4. 4. ṁ2 = 633.3 kg/h
  5. 5. P = 1175 kg/h
  6. 6. P = 1955 kg/h

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