7-1. In the production of formaldehyde ( CH 2O ) by catalytic oxidation of methanol ( CH 3OH ), an
equimolar mixture of methanol and air (21% oxygen and 79% nitrogen) is sent to a catalytic reactor. The
reaction is catalyzed by finely divided silver suppo

5-20. An equi-molar mixture of ethanol and ethyl ether is kept in a closed container at 103 KPa
and 95 C. The temperature of the container is slowly reduced to the dew point of the mixture.
Determine:
(a) What is the dew point temperature of the mixture?

Problem 7-5 . A process yields 10,000 ft3 per day of a mixture of hydrogen chloride and air. The volume fraction
of HCl is 0.062, the temperature of the mixture is 550F, and the total pressure is represented by 29.2 inches of
mercury. Calculate the mass o

Chapter 3
Conservation of Mass for
Single Component Systems
In Chapter 1, we pointed out that much of chemical engineering is concerned with keeping track of
molecular species during processes in which chemical reactions and mass transport take place. How

5-16. In this problem, we examine the process of recovering fission materials from spent nuclear
fuel rods. This is usually referred to as reprocessing of the fuel to recover plutonium, Pu, and the
active isotope of uranium, U235. Reprocessing can be done

Problem 7-5 . A process yields 10,000 ft3 per day of a mixture of hydrogen chloride and air. The volume fraction
of HCl is 0.062, the temperature of the mixture is 550F, and the total pressure is represented by 29.2 inches of
mercury. Calculate the mass o

UNIVERSITY OF CALIFORNIA
Department of Chemical Engineering and Materials Science
ECH51
Material Balances
First In-class Exam (Practice Exam)
(No solutions provided)
Prof. Brian G. Higgins
Winter 2008
Given for Exam:
Total Mass Balance
t
HtL
r V +
Speci

4-2. A liquid hydrocarbon mixture was made by adding 295 kg of benzene, 289 kg of toluene and 287 kg of p-xylene. Assume there is no change of volume upon mixing, i.e., Vmix = 0 , in order to determine: 1. The species density of each species in the mixtur

5-19. A saturated solution of calcium hydroxide enters a boiler as shown in Figure 5.19 and a
fraction, , of the water entering the boiler is vaporized. Under these circumstances a portion of
the calcium hydroxide precipitates and you would like to know t

Example Problem
Problem 3 (10 points)
In the production of a bean oil, beans containing 13.0 wt% oil(A) and 87.0 wt% solid (B) are ground and fed into
a stirred tank(the extractor) along with a recycled stream of liquid n-hexane(C). The feed ratio is 3kg

Appendix A
A1 Atomic Mass of Common Elements Referred to Carbon-12 1
Element
Aluminum
Antimony
Argon
Arsenic
Barium
Beryllium
Bismuth
Boron
Bromine
Cadmium
Calcium
Carbon
Cerium
Cesium
Chlorine
Chromium
Cobalt
Copper
Fluorine
Gallium
Germanium
Gold
Hafniu

Appendix E
Conservation of Charge
In Chapter 6 we represented the conservation of atomic species by
A N
N
Axiom II:
JA
0,
RA
J 1, 2,., T
(E-1)
A 1
and in matrix form we expressed this result as
Axiom II:
N11
N 21
N
31
.
.
NT 1
N12
N13 . N1, N 1,
N 22

Nomenclature
A
area, m2, absorption factor
A
closed surface area of the control volume V , m2
Aa (t )
closed surface area of an arbitrary, moving control volume Va (t ) , m2
Ae
area of the entrances and exits for the control volume V , m2
Ae (t )
area of

Appendix F
Heterogeneous Reactions
Our analysis of the stoichiometry of heterogeneous reactions is based on conservation of atomic
species expressed as
A N
N
Axiom II:
0
JA R A
(F-1)
A1
We follow the classic continuum point of view 1 and assume that this

Appendix D
Atomic Species Balances
Throughout this text we have made use of macroscopic mass and mole balances to solve a variety of
problems with and without chemical reactions. Our solutions have been based on the application of
Axiom I and Axiom II, an

8-1. A tank containing 200 gallons of saturated salt solution (3 lbm of salt per gallon) is to be
diluted by the addition of brine containing 1 lbm of salt per gallon. If this solution enters the tank
at a rate of 4 gallons per minute and the mixture leav

8-2. A salt solution in a perfectly stirred tank is washed out with fresh water at a rate such that the
average residence time, V / Q , is 10 minutes. Calculate the following:
a) The time in minutes required to remove 99% of the salt originally present
b)

Problem 8-11
A batch reactor illustrated in figure 8-11 is used to study the irreversible, decomposition reaction
A
k
products
The proposed chemical kinetic rate equation is
RA = - k cA
and this decomposition reaction is catalyzed by sulfuric acid. To ini

Prob 8-18
Repeat the analysis of binary distillation when Raoults law is applicable, .i.e, the process equilibrium relation is given by
aeff XxA \
XyA \exit =
1 + XxA \ Haeff - 1L
Herre aeff is the effective relative volatility and is temperature dependen

ReactionProb7_08
Ethylene oxide (EO: C2 H4 O) is produced by the catalytic oxidation of ethylene (E: C2 H4 ). An undesired competing reaction is
the combustion of ethylene to form CO2 and H2 O
The feed to the reactor Stream #2 (not the fresh feed to the p

7-1. A flue gas (stream #1) composed of carbon monoxide, carbon dioxide, and nitrogen can
undergo reaction with water gas (stream #2) and steam to produce the synthesis gas (stream #3)
for an ammonia converter. The carbon dioxide in the synthesis gas must

ReactionProblem 8
Ethylene oxide (EO: C2 H4 O) is produced by the catalytic oxidation of ethylene (E: C2 H4 ). An undesired competing reaction is
the combustion of ethylene to form CO2 and H2 O
The feed to the reactor Stream #2 (not the fresh feed to the

3-14. In Figure 3.14 we have illustrated a cross-sectional view of a barge loaded with stones. The barge has sprung a lead as indicated, and the volumetric flow rate of the leak is given by
leak flow rate = Cd Ao g (h hi )
Here Cd is a discharge coefficie

8-4. Three perfectly stirred tanks, each of 10,000 gallon capacity, are arranged so that the effluent
of the first is the feed to the second and the effluent of the second is the feed to the third. Initially
the concentration in each tank is co . Pure wat

4-26.
In a glycerol plant, a 10% (mass basis) aqueous glycerin solution containing 3% NaCl is
treated with butyl alcohol as illustrated in Figure 4.26. The alcohol fed to the tower contains 2%
water on a mass basis. The refinate leaving the tower contains

Appendix C
Matrices and Stoichiometric Schemata
In Appendix C1 we review concepts associated with matrix algebra. In Appendix C2 we illustrate how
one can transform an equation to a picture in a rigorous manner, and this leads to a schema for a single
ind

Appendix B
Iteration Methods
B1. Bisection method
Given some function of x such as H ( x ) , we are interested in the solution of the equation
H ( x) 0 ,
x x
(B-1)
Here we have used x to represent the solution. For simple functions such as H ( x ) x b we

Chapter 2
Units
There are three things that every engineer should understand about units. First, the fundamental
significance of units must be understood. Second, the conversion from one set of units to another 1 must be
a routine matter. Third, one must

UNIVERSITY OF CALIFORNIA
Department of Chemical Engineering and Materials Science
ECH51
Material Balances
First In-class Exam (Practice Exam)
(No solutions provided)
Prof. Brian G. Higgins
Winter 2007
Given for Exam:
Total Mass Balance
r V +
r Hv - wL

HANOI UNIVERSITY OF MINING AND GEOLOGY
ECH 51
Material Balances
Pactice Exam
(Closed book and notes, calculators allowed)
Prof. Brian G. Higgins
April 2012
Given for Exam:
Total Mass Balance
t
V HtL
r V +
A HtL
r Hv - w L n A = 0
Species Mass Balance (n

Hanoi University of Mining and Geology
Chemical Engineering Program
ECH 51 Material Balances for Chemical Engineers
June 2014
Homework Assignments: Chapter 5, 6, and 7
Problem 5-24: Due Tuesday June 16
Problem 5-28: Due Wednesday June 17
Problem 6-10: Due