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This chapter is from the book

Review Questions

1.1 What is meant by a concentration jump?

1.2 What is meant by the continuum assumption and what are its implications in model development?

1.3 Indicate some situations where the continuum models are unlikely to apply.

1.4 Give an example of a system in which the total concentration is (nearly) constant.

1.5 Give an example of a system in which the mixture density is nearly constant.

1.6 Can average molecular weight be a function of position?

1.7 Which information is missing in the differential models based on the continuum assumption?

1.8 Why are constitutive models needed in the context of differential models?

1.9 Does the Fick’s law apply universally to all systems?

1.10 Write a form of Fick’s law using partial pressure gradient as the driving force.

1.11 What is meant by the invariant property of the flux vector?

1.12 The combined flux is partitioned into the sum of the convection flux and the diffusion flux. Is this partitioning unique?

1.13 State the units of the gas constant if the pressure is expressed in bar instead of Pa, (ii) if expressed in atm.

1.14 Express the dissolved oxygen concentration in Example 1.1 in parts per million (ppm).

1.15 What is a macroscopic-level model? Which information needs to be added in such a model in addition to the conservation principle?

1.16 How is the mass transfer coefficient defined? Why is it needed?

1.17 What is meant by a cross-sectional average concentration? What is a cup mixing or the bulk concentration?

1.18 Which assumptions are involved in a plug flow model?

1.19 Which assumptions are involved in a completely backmixed model?

1.20 Which additional closure is needed for mass transport in turbulent flow? Why?

1.21 What is an ideal stage contactor? How do you correct the model if the stage is not ideal?

1.22 What is the dispersion coefficient and where is it needed?

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