CHE 205 $200 $400 $600 $800 $1000 Vapor/Liquid Equilibrium Energy Balances Multiphase Systems...
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Transcript of CHE 205 $200 $400 $600 $800 $1000 Vapor/Liquid Equilibrium Energy Balances Multiphase Systems...
CHE 205
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Vapor/Liquid Vapor/Liquid EquilibriumEquilibrium
Energy Energy BalancesBalances
Multiphase Multiphase SystemsSystems
Nonreactive Nonreactive ProcessesProcesses
$600
How can you tell How can you tell which of two which of two
components is more components is more volatile?volatile?
What can you say about the What can you say about the bubble point and dew point bubble point and dew point temperatures of a mixture temperatures of a mixture of two components A and B of two components A and B (T(T⁰⁰b,Ab,A < T < T⁰⁰b,Bb,B)? What about )? What about
the compositions of the first the compositions of the first bubble and last drop of bubble and last drop of
mixture?mixture?
Explain why a soda can Explain why a soda can fizzes when it is fizzes when it is
openedopened
Draw the temperature plot Draw the temperature plot for heating pure for heating pure
cyclohexane from 20 C to cyclohexane from 20 C to 100 C at a pressure of 1 100 C at a pressure of 1
atm. State what is atm. State what is happening in each region of happening in each region of
the curve.the curve.
Write the equations to solve Write the equations to solve for the temperature and for the temperature and
composition of a liquid in composition of a liquid in equilibrium with a vapor that equilibrium with a vapor that is 30 mole% acetone-70 moleis 30 mole% acetone-70 mole% ethanol at 1 atm. Is this a % ethanol at 1 atm. Is this a
bubble-point or dew-point bubble-point or dew-point calculation? List vapor calculation? List vapor
pressures as a variable and pressures as a variable and state where you would find state where you would find
them.them.
What can you say What can you say about the enthalpy of a about the enthalpy of a system of air at 600 system of air at 600 ⁰⁰F F and 1 atm? The value and 1 atm? The value given in Table B.9 is given in Table B.9 is
3719 BTU/lbmol3719 BTU/lbmol
Cancel the terms of the energy Cancel the terms of the energy balance of the following balance of the following system and explain if the system and explain if the
remaining terms are positive remaining terms are positive or negativeor negative
IsothermalIsothermal
CondenserCondensermm1 1 kg Hkg H22O O
(v)/hr(v)/hr
P = 20 barP = 20 bar
T = 250 CT = 250 C
mm2 2 kg Hkg H22O O (v)/hr(v)/hr
P = 40 bar, P = 40 bar, sat’dsat’dmm3 3 kg Hkg H22O O (l)/hr(l)/hr
Complete the following table Complete the following table for waterfor water
State T (°C) P (bar) V (m3/kg)
U (kJ/kg)
Table
Vapor 50 Sat’d
Liquid 94 1
Vapor Sat’d 0.538
450 40
One thousand kilograms per hour One thousand kilograms per hour of steam drives a turbine. The of steam drives a turbine. The
steam enters the turbine at 60 bar steam enters the turbine at 60 bar and 450C. The turbine delivers and 450C. The turbine delivers
shaft work at a rate of 70 kW and shaft work at a rate of 70 kW and the heat loss is 20 kW. Calculate the heat loss is 20 kW. Calculate the final temperature of the steam the final temperature of the steam
if the final pressure is 0.5 bar.if the final pressure is 0.5 bar.
If a pump is 70 % efficient, how If a pump is 70 % efficient, how many kW are necessary to pump many kW are necessary to pump water flowing at 10 kg/s from a water flowing at 10 kg/s from a lake at 1 bar to an outlet 75 m lake at 1 bar to an outlet 75 m above the lake at 5 bar, if the above the lake at 5 bar, if the
outlet pipe has a 4 cm ID?outlet pipe has a 4 cm ID?
Define a colligative Define a colligative solution property? solution property? Name 3 of them.Name 3 of them.
Without using your Without using your book, what is the book, what is the
definition of bubble-definition of bubble-point and dew-point point and dew-point temperatures? What temperatures? What assumptions must be assumptions must be
made to apply Raoult’s made to apply Raoult’s or Henry’s Laws?or Henry’s Laws?
What is the dew point and composition of a What is the dew point and composition of a mixture of 70% 1-propanol with the rest 1-mixture of 70% 1-propanol with the rest 1-
pentanol in the vapor phase? pentanol in the vapor phase?
600
1000
1400
1800
2200
2600
3000
0 0.2 0.4 0.6 0.8 1
P (m
mH
g)
mole fraction 1-propanol
Pxy diagram at 135 ⁰C for 1-propanol and 1-pentanol mixture
Given the following Txy diagram for styrene Given the following Txy diagram for styrene in toluene at 1000 mm Hg, if a mixture with in toluene at 1000 mm Hg, if a mixture with 40 mole% of styrene is fed to an evaporator 40 mole% of styrene is fed to an evaporator what is the bubble-point temperature and what is the bubble-point temperature and
the equilibrium vapor composition?the equilibrium vapor composition?
110
120
130
140
150
160
0 0.2 0.4 0.6 0.8 1
T (⁰
C)
mole fraction styrene
Txy diagram at 1000 mmHg for styrene-toluene mixture
A gas containing OA gas containing O22 is in is in equilibrium with liquid water equilibrium with liquid water containing a small amount of containing a small amount of OO22 at 30C and 3 atm. Would at 30C and 3 atm. Would
you use Raoult’s Law or you use Raoult’s Law or Henry’s Law to estimate the Henry’s Law to estimate the
relationship betweenrelationship between
a.a.xxO2O2 and p and pO2O2
b.b. xxH2OH2O and p and pH2OH2O
and why?and why?
If HCN is taken from If HCN is taken from 25°C to 100°C, both 25°C to 100°C, both
states at 1 atm, but was states at 1 atm, but was carried out in such a way carried out in such a way that the pressure varied that the pressure varied during the heating, can during the heating, can
you still use Cyou still use Cpp to to calculate the specific calculate the specific
enthalpy and why?enthalpy and why?
Estimate the heat Estimate the heat capacity of solid CaCOcapacity of solid CaCO33
using Kopp’s Ruleusing Kopp’s Rule
Calculate the specific Calculate the specific enthalpies of the enthalpies of the
following processes:following processes:
a.a.NN22 (25°C to 700°C) (25°C to 700°C)
b.b.HH22 (800°F to 225°F) (800°F to 225°F)
Draw the process path of Draw the process path of n-pentane going from a n-pentane going from a solid at -150°C and 0.5 solid at -150°C and 0.5 atm to a vapor at 100°C atm to a vapor at 100°C and 4.0 atm. List where and 4.0 atm. List where
you would find the you would find the information to calculate information to calculate
ΔΔH for each step, but H for each step, but don’t calculate any of don’t calculate any of
them.them.
Suppose the formula Suppose the formula
was used to calculate the specific was used to calculate the specific enthalpy change for a change in enthalpy change for a change in
temperature and pressure fortemperature and pressure for
a.a. An ideal gasAn ideal gas
b.b.A highly nonideal gasA highly nonideal gas
c.c. A liquidA liquid
For which situation is the formula For which situation is the formula exact and which would have error?exact and which would have error?
2
1
)(ˆT
T
p dTTCH