Modern Engineering Thermodynamics

646 CHAPTER 15: Chemical Thermodynamics
alcohol of this type, C n H 2n + 1 ðOHÞ, in 100.% theoretical air and
test it out with
a. Methyl alcohol (also known as methanol or wood alcohol),
CH 3 ðOHÞ:
b. Ethyl alcohol (also known as ethanol or grain alcohol),
C 2 H 5 ðOHÞ.
c. Isopropyl alcohol, C 3 H 7 ðOHÞ:
24. Propane, C 3 H 8 , is burning with 130.% theoretical air in a camp
stove. Determine
a. The reaction equation.
b. The molar air/fuel ratio of the combustion.
c. The volumetric analysis of the combustion products.
d. The dew point temperature of the combustion products
if the total pressure of the combustion products is 14.7 psia.
25. The combustion of an unknown amount of benzene (x moles
of C 6 H 6 ) in pure oxygen in a chemical reactor produces the
following dry exhaust gas analysis: 44.71% CO 2 and 55.29% O 2 .
Determine
a. The actual molar and mass fuel/oxygen ratios.
b. The percent of theoretical oxygen used.
c. The molar percentage of water vapor in the exhaust gas
before it was dried for this analysis.
26. The combustion of an unknown amount of ethylene (x moles of
C 2 H 4 ) in pure oxygen in a laboratory experiment produces the
following dry exhaust gas analysis on a molar basis: 84.75%
CO 2 and 15.25% O 2 : Determine
a. The actual molar and mass oxygen/fuel ratios.
b. The percent of excess oxygen used.
c. The molar percentage of water vapor in the exhaust gas
before it was dried for this analysis.
27. The combustion of an unknown amount of acetylene (x moles
of C 2 H 2 ) with pure oxygen in an oxyacetylene torch produces
the following dry exhaust gas analysis: 39.14% CO 2 and 60.86%
O 2 : Determine
a. The actual molar and mass fuel/oxygen ratios.
b. The percent of excess oxygen used.
c. The molar percentage of each combustion product before the
exhaust gas was dried for this analysis.
28. An unknown amount of butane (x moles of C 4 H 10 ) is burned
with pure oxygen in a bomb calorimeter. The dry gas molar
analysis of the products is 48.72% CO 2 and 51.28% O 2 :
Determine
a. The actual molar and mass oxygen/fuel ratios.
b. The percent excess oxygen used.
c. The molar percentage of each combustion product before the
exhaust gas was dried for this analysis.
29. The combustion of an unknown amount of methane (x moles
of CH 4 ) in a furnace results in the following dry exhaust gas
molar analysis: 9.52% CO 2 , 4.00% O 2 , and 86.47% N 2 :
Determine
a. The actual molar and mass air/fuel ratios.
b. The percent of excess air used.
c. The molar percentage of water vapor in the exhaust gas
before it was dried for this analysis.
30. The combustion of an unknown amount of propane (x moles of
C 3 H 8 ) in an industrial oven produces the following dry exhaust
gas analysis on a volume basis: 5.52% CO 2 , 12.59% O 2 , and
81.89% N 2 : Determine
a. The actual molar and mass air/fuel ratios.
b. The percent of theoretical air used.
c. The volume percentage of water vapor in the exhaust gas
before it was dried for this analysis.
31. An unknown amount of ethane (x moles of C 2 H 6 ) is burned in
a combustion chamber with air. The dry gas molal analysis of
the exhaust products is 6.64% CO 2 , 10.46% O 2 , and 82.9% N 2 :
Determine
a. The actual molar and mass fuel/air ratios.
b. The percent of excess air used.
c. The molar percentage of each combustion product before the
exhaust gas was dried for this analysis.
32. The combustion of an unknown amount of propylene (x moles
of C 3 H 6 ) with air in a prototype space heater produced the
following dry exhaust gas molar analysis: 4.27% CO 2 , 15.05%
O 2 , and 80.68% N 2 : Determine
a. The actual molar and mass air/fuel ratios.
b. The percent of theoretical air used.
c. The molar percentage of each combustion product before the
exhaust gas was dried for this analysis.
33. The following dry exhaust volumetric analysis results from the
combustion of an unknown amount of octane (x moles of
C 8 H 18 ) in a spark ignition internal combustion engine: 8.80%
CO 2 , 8.20% CO, 4.1% H 2 , 1.00% NO, 0.200% CH 4 , and
77.7% N 2 : Determine
a. The actual molar and mass air/fuel ratios.
b. The percent of theoretical air used.
c. The molar percentage of water vapor in the exhaust gas
before it was dried for this analysis.
34. The following dry exhaust gas molar analysis results from the
combustion of an unknown amount of kerosene (x moles of
C 10 H 22 ) in a compression ignition internal combustion engine:
6.30% CO 2 , 9.40% CO, 4.70% C, 4.70% H 2 , 1.50% NO,
0.200% CH 4 , and 73.2% N 2 : Determine
a. The actual molar and mass air/fuel ratios.
b. The percent deficit air used.
c. The volumetric percentage of water vapor in the exhaust
gas before it was dried for this analysis.
35. An unknown hydrocarbon material is burned in a calorimeter
with air. An Orsat analysis indicates that the (dry) exhaust gas is
made up of only 17.5% CO 2 and 82.5% N 2 , with no CO or O 2
present. Determine
a. The fuel model ðC n H m Þ:
b. The composition of the fuel on a mass basis.
c. The percent theoretical air used.
d. The dew point temperature if the combustion products are at
0.101 MPa.
36.* An unknown hydrocarbon material is burned in air for chemical
analysis. An Orsat test indicates that the (dry) exhaust gas
contains no CO or O 2 but consists of only 14.9% CO 2 and
85.1% N 2 : Determine
a. The fuel model ðC n H m Þ:
b. The composition of the fuel on a percent mass basis.
c. The molar and mass air/fuel ratios used in the combustion
process.
d. The dew point temperature if the combustion products are at
0.101 MPa.
37. An Orsat analysis of the (dry) products of combustion of a gas
emanating from the bowels of a creature of immense hypocrisy
produces the following composition: 1.00% CO 2 , 19.2% O 2 ,
and 79.8% N 2 : Determine
a. The chemical formula ðC n H m Þ and name of the gas.
b. The composition of the fuel on a percent molar basis.