Chemical Engineering 140 August 26, 2015
Problem Set #1
(Due Wednesday, September 2)
* stands for Himmelblau and Riggs, 8th edition. Problem numbers without an asterisk are
from Felder and Rousseau.
1. *2.3.6
The velocity in a pipe in turbulent flow is expressed by the following equation:
where τ is the shear stress in N/m2, u is the velocity in m/s, and k is a coefficient. You
are asked to modify the equation so that the shear stress can be introduced in the units of
τ’ which are lbf/ft2, and the density ρ’ for which the units are lb/ft3 so that the velocity u’
comes out in units of ft/s. Show all calculations, and give the final equation in terms of
u’,τ’, and ρ’so a reader will know that American Engineering units are involved in the
equation.
2.
3.
Misuse of significant figures in engineering is unacceptable. Do not just
report calculated digits!
4. A liquefied mixture of n-butane, n-pentane, and n-hexane has the following mass
composition:
n-C4H10 50%
n-C5H12 30%
n-C6H14 20%
For this mixture, calculate:
a. The weight fraction of each component.
b. The mole fraction of each component
c. The mole percent of each component.
d. The average molecular weight of the mixture.
e. Assume that the condition of the liquefied mixture is now changed to ambient
temperature and 3 bar where it is an ideal gas. What is the mass density of each
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