Questions and Answers of Chemical Biochemical And Engineering

Redo Problem 13.25 using Aspen Plus.Problem 13.25When pure hydrogen iodide gas enters an evacuated cylinder, the following reactions may occur: (Note that since Gibbs energies of formation data are
Redo Problem 13.23 using Aspen Plus.Problem 13.23Consider a gaseous mixture containing the three isomers n-pentane (1), iso-pentane (2), and neo-pentane (3). These species may interconvert by
Redo Problem 13.21 using Aspen Plus.Problem 13.21Styrene can be hydrogenated to ethyl benzene at moderate conditions in both the liquid phase and the gas phase. Calculate the equilibrium compositions
Redo Problem 13.18 using Aspen Plus.Problem 13.18By catalytic dehydrogenation, 1-butene can be produced from n-butane,C4H10 = C4H8 + H2However, 1-butene may also be dehydrogenated to form
Redo Problem 13.17 using Aspen Plus.Problem 13.17The simple statement of the Le Chatelier-Braun principle given in Sec. 13.1 leads one to expect that if the concentration of a reactant were
Redo Problem 13.15 using Aspen Plus.Problem 13.15When propane is heated to high temperatures, it pyrolyzes or decomposes. Assume that the only reactions that occur are and that these reactions take
Redo Problem 13.14 using Aspen Plus.Problem 13.14Acetaldehyde is produced from ethanol by the following gas-phase reactions: The reactions are carried out at 540°C and 1 bar pressure using a silver
Redo Problem 13.12 using Aspen Plus.Problem 13.12Ethylene dichloride is produced by the direct chlorination of ethylene using small amounts of ethylene dibromide as a catalyst: If stoichiometric
Redo Problem 13.11 using Aspen Plus.Problem 13.11An important step in the manufacture of sulfuric acid is the gas-phase oxidation reaction Compute the equilibrium conversion of sulfur dioxide to
Redo Problem 13.10 using Aspen Plus.Problem 13.10Hydrogen gas can be produced by the following reactions between propane and steam in the presence of a nickel catalyst:a. Compute the standard heat of
Redo Problem 13.5 using Aspen Plus.Problem 13.5The production of NO by the direct oxidation of nitrogen,occurs naturally in internal combustion engines. This reaction is also used to commercially
Redo Problem 13.3 using Aspen Plus.Problem 13.3Carbon dioxide can react with graphite to form carbon monoxide, and the carbon monoxide formed can further react to form carbon and oxygen: Determine
Redo Problem 13.1 using Aspen Plus.Problem 13.1Isopropyl alcohol is to be dehydrogenated in the gas phase to form propionaldehyde according to the reaction Compute the equilibrium fraction of
Adenosine monophosphate (AMPH) is a nucleotide that is present as a monomer in DNA and RNA. It consists of a phosphate group, a ribose molecule and an adenine molecule. Consequently, it can be found
Starting with an equimolar mixture of acetaldehyde and NAD+ at 25°C, calculate and plot the extent of the following reaction as a function of pH. Also determine the pH at which half the acetaldehyde
Starting with an equimolar mixture of methanol and NAD+ at 25°C, calculate and plot the extent of the following reaction as a function of pH:For this reaction at solution conditions, the apparent
Starting with an equimolar mixture of lactate and NAD+ at 25°C, calculate and plot the extent of the following reaction as a function of pH:where R is a side group. For this reaction at solution
Determine the charge on tyrosine as a function of pH. Tyrosine (C9H11NO3), another amino acid in proteins, has two dominant ionizable groups with pKHA values of 2.24 and 9.04 at 25°C (and a third,
a. Prove that the isoelectric point for an amino acid with two ionization sites is b. Develop an equation for the calculation of the isoelectric point of an amino acid or protein with three
L-cystine C6H12N2O4S2 has four ionization states with the following values for its ionization constants:Determine the charge on L-cystine as a function of pH. pK₁ = 1.0 pK₂ = 2.1 and
Oxaloacetic acid C4H4O5 has the following values for its ionization constants:Determine the charge on oxaloacetic acid as a function of pH. pK₁ = 2.55 pK₂ = 4.37 and and pK3 pK3 13.03 =
Oxalic acid C2H2O4 is a dibasic acid with the following values for its ionization constants:Determine the charge on oxalic acid as a function of pH. pK₁ = 1.2 and pK₂ = 4.2
Creatine C4H9N3O2 has been used by body builders and athletes to increase muscle mass and strength. Its chemical structure (not showing all of its carbon atoms and attached hydrogens) isThe
The compound levodopa C9H11NO4 (usually referred to a L-dopa) is used in the treatment of Parkinson’s disease. The chemical structure (not showing its carbon atoms and attached hydrogens) isThe
The following values are known for the amino acid serine C3H7NO2S:Determine the charge on this amino acid as a function of pH. How does your result compare with the reported isoelectric point (pI)
Derive the equation that replaces Eq. 13.6-3 for a protein that has six ionizable sites. Macid = MH₂A + MHA- + MA²_ = MH₂A + K₁ MH₂A 1+ [₁ = K₁ MH+ + K₂ (MH+)²] . MH₂A. K₁
An equimolar mixture of methanol and acetic acid react in the liquid phase at 150°C and 5 bar to form methyl acetate and water. Determine the equilibrium composition at these conditions. (Assume the
An equimolar mixture of ethylene and hydrogen chloride react in the gas phase at 150°C and 10 bar to form ethyl chloride. Determine the equilibrium composition at these conditions.
Photosynthesis to produce sucrose C12H22O11 can be considered to occur by the following reactionHow much Gibbs free energy at 25°C must be obtained from sunlight for each mole of sucrose produced?
Another way to reduce the amount of nitric oxide is exhaust gasses is to inject ammonia resulting in the following reaction Determine the equilibrium conversion of nitric oxide at 1000°C and 1 bar
A way to reduce the amount of nitric oxide from the exhaust of diesel automobile engines is to inject urea resulting in the following reaction Determine the equilibrium conversion of nitric oxide at
For the reaction in Problem 13.69, at 5 bar determine the equilibrium temperature for 95% conversion of coal by this reaction. Is the reaction endothermic or exothermic at this temperature?Problem
Consider the following reaction for producing hydrogen starting from coal (carbon) at 1 bar Determine the equilibrium conversion of coal at 750 K and 5 bar. Is the reaction endothermic or exothermic
It is possible that oxygen and other gases dissociate when adsorbed on a solid surface, and in catalysis it is important to know whether such a dissociation occurs. If oxygen did not dissociate, that
At an appropriate temperature, a larger alkane will “crack” to former a smaller alkane and an olefin. One example is the cracking of propane to form methane and ethylene a. Calculate the
The following equilibrium constants have been found experimentally when CO2 is in contact with waterCompute the pH of water at each of the CO2 concentrations in air. CO₂ (gas) → CO₂
It has been suggested that as the carbon dioxide concentration in the atmosphere increases, the ocean surface water will become more acidic, which will have a serious effect on fish and coral. The
Ammonia, air and water is to be converted to a nitric acid solution. Ammonia is available as a liquid at 25°C and its saturation pressure, air and water (as a liquid) are available at 1.013 bar and
The amino acid dl-alanine HCOO-CNH2H-CH3 exists in the following four forms in solutionDetermine the fraction of dl-alanine in each of these forms at a. pH = 3 b. pH = 10 K₁ NH CH₂COOH H+ +
Redo Illustration 13.5-2 including the ionization of water and including the effect of solution nonidealities.Illustration 13.5-2A common analytical procedure is titration, in which a solution of a
Derive the equation that replaces Eq. 13.5-16 if the thermodynamic equilibrium constant (rather than the apparent equilibrium constant) is used and electrolyte solution nonideality is included. MH+
Derive the equation that replaces Eq. 13.5-16 for the case of a weak base and a strong acid. MH+ = aMHA,0 – MBOH -(KHA +MBOH)+ √(KHA - MBOH)² +4KHA MHA,O (13.5-16) 2 .
Derive the equations that replace Eqs. 13.5-12a and b if the thermodynamic equilibrium constant (rather than the apparent equilibrium constant) is used and electrolyte solution nonideality is
Derive the equation that replaces Eq. 13.5-11 if the thermodynamic equilibrium constant (rather than the apparent equilibrium constant) is used and electrolyte solution nonideality is included. pH
Derive Eqs. 13.5-8a and b. Мон- MH+ = = 1 {{ MBOH + (MBOH)² + Ka,w (M = 1)² MOH-7² 22 W 4Ka,w Y² (M = 1)² Kaw (M = 1)² MBOHY (13.5-8a) Ka,w (M = 1)² Ka, [MBON + √(MBOH)² + 4%, (M = 1)²
Using the values for the equilibrium constant for the ionization of water in Table 13.5-1, estimate the standard-state heat of ionization of water as a function of temperature. Also, determine the pH
The behavior of hydrogen fluoride is unusual! For example, here are the critical properties of various hydrogen halides: has the lowest reported critical compressibility of any species. Experimental
The description of components that associate or hydrogen-bond is difficult. An alternative model to the one considered in the previous problem is the continuous association model, in which Assume
Assume two species can associate in the vapor phase according to the reactionsUsing the notation that G̅A and G̅B are the partial molar Gibbs energies of the total species A and B (in all its
At low temperatures mixtures of water and methane can form a hydrate, that is, a solid containing trapped methane. Hydrates have both positive and negative features. For example, they are potentially
Very polar molecules may associate in the gas phase. One example is acetic acid, which, because of its structure, can form dimers but not higher polymers. For the reaction These values are for the
The chemical reaction for the dissociation of nitrogen tetroxide is N2O4(g) → 2NO2(g)The reported standard-state Gibbs energy change for this reaction over a limited temperature range isfor the
While ethanol can be made by biological fermentation, for large-scale production the following nonbiological reaction starting with ethylene and water can be used instead: If stoichiometric amounts
a. Use the data in Table 13.1-4 and the information that ΔfG°AgCl = −108.7 kJ/mol to predict the solubility product K°AgCl of silver chloride in water, and compare your predictions with the data
At high temperatures—for example, in a combustion process—nitrogen and oxygen in air can react to form nitrous oxide, Starting with air (79 mol % nitrogen and 21 mol % oxygen), compute the
The dissociation of hydrogen selenide gas to produce pure selenium may be approximated as occurring by the reaction for which ΔrxnG = 89.38 − 0.0879T in kJ and T in K. Over the temperature range
a. One mole of calcium carbonate is placed in an evacuated 10-liter cylinder and heated to 1150 K. Compute the extent of dissociation of calcium carbonate to calcium oxide and the pressure in the
Gases can be (very) slightly soluble in molten metals. For example, the solubility of nitrogen in liquid iron is well correlated by the empirical expression One question that arises is whether the
The proteolytic enzyme α-chymotrypsin is known to dimerize. The following data are available for this reaction at 25°C and pH = 7.8.based on ideal 1 M standard states. a. Determine the values of
It is possible that hydrogen and other gases dissociate when adsorbed on a solid surface, and in catalysis it is important to know whether such a dissociation occurs. If hydrogen did not dissociate,
At an appropriate temperature, a larger alkane will “crack” to form a smaller alkane and an olefin. One example is the cracking of propane to form methane and ethylene: a. Calculate the
Formaldehyde is an important industrial solvent and also a raw material in chemical manufacture. At elevated temperatures, it dissociates into ammonia and carbon monoxide in the following gas-phase
Consider a closed vessel in which selenium is in equilibrium with its vapor. Selenium, in the vapor phase, polymerizes to Sei species where i = 1, 2, 3, 5, 7, 8. a. At any temperature above the
Liquid benzene can be catalytically hydrogenated, with cyclohexene, cyclohexane, and 1,3-cyclohexadiene being among the products. Determine the product distribution as a function of the hydrogen
The liquid in a two-phase, binary mixture of benzene and cyclohexane has a composition of 20 mol % of benzene and 80 mol % of cyclohexane at T = 80°C. a. Find the pressure of the system and the
A process is being developed to produce high-purity titanium. As part of the proposed process, titanium will be kept in a quartz (silicon dioxide) crucible at 1273 K. A chemical engineer working on
A gas mixture containing equimolar quantities of carbon dioxide and hydrogen is to be “reformed” by passing it over a catalyst. The pressure in the reformer will be determined by the possibility
Carbon is deposited on a catalytic reactor bed as a result of the cracking of hydrocarbons. Periodically, hydrogen gas is passed through the reactor in an effort to remove the carbon and to preserve
The calcination of sodium bicarbonate takes place according to the reaction When this reaction was run in the laboratory by placing sodium bicarbonate in an initially evacuated cylinder, it was
When pure hydrogen iodide gas enters an evacuated cylinder, the following reactions may occur: (Note that since Gibbs energies of formation data are available for iodine in both the gaseous and
Methane gas hydrates are formed from liquid water by the following reaction: a. Calculate the Gibbs energy of formation of the hydrate at 278 K and 283 K using the information that the methane
Consider a gaseous mixture containing the three isomers n-pentane (1), iso-pentane (2), and neo-pentane (3). These species may interconvert by reaction. a. Determine the number of independent
If 1 mole of a gas in a constant-volume system is heated, and both the heat flow and the gas temperature are measured as a function of time, the constant volume heat capacity can be computed
Styrene can be hydrogenated to ethyl benzene at moderate conditions in both the liquid phase and the gas phase. Calculate the equilibrium compositions in the vapor and liquid phases of hydrogen,
Silver, when exposed to air, tarnishes. The following reactions have been proposed for this tarnishing: The following data are available: Air can be assumed to contain 0.5 ppm H2, 0.03 ppm (80
By catalytic dehydrogenation, 1-butene can be produced from n-butane,C4H10 = C4H8 + H2However, 1-butene may also be dehydrogenated to form 1,3-butadiene,C4H8 = C4H6 + H2Compute the equilibrium
As part of the process of glycogen breakdown and utilization in muscles, glucose 1-phosphate is converted to glucose 6-phosphate (that is, the phosphate group on a glucose molecule moves from the
When propane is heated to high temperatures, it pyrolyzes or decomposes. Assume that the only reactions that occur are and that these reactions take place in the gas phase. a. Calculate the
Acetaldehyde is produced from ethanol by the following gas-phase reactions: The reactions are carried out at 540°C and 1 bar pressure using a silver gauze catalyst and air as an oxidant. If 50%
Polar molecules interact more strongly at large distances than do nonpolar molecules, and generally form nonideal solutions. One model for solution nonidealities in a binary mixture consisting of a
Ethylene dichloride is produced by the direct chlorination of ethylene using small amounts of ethylene dibromide as a catalyst: If stoichiometric amounts of ethylene and chlorine are used, and the
An important step in the manufacture of sulfuric acid is the gas-phase oxidation reactionCompute the equilibrium conversion of sulfur dioxide to sulfur trioxide over the temperature range of 0 to
The data in the following table give the solubility of silver chloride in various aqueous solutions at 25°C. Show that these data can be plotted on the same ln Ks versus √I curve as used in
Carbon disulfide is produced from the high-temperature reaction of carbon and sulfur:C(s) + S2(g) = CS2(g)This reaction is carried out in a retort at low pressure, and in the absence of oxygen and
Crystalline sodium sulfate, in the presence of water vapor, may form a decahydrate, Na2SO4(s) + 10H2O(g) = Na2SO4·10H2O(s) a. Estimate the minimum partial pressure of water at which the
The extent of reaction generally depends on pressure as well as temperature. For the reaction (or phase transition) the standard-state Gibbs energy change at 25°C is 2866 J/mol. The density of
Carbon dioxide can react with graphite to form carbon monoxide, and the carbon monoxide formed can further react to form carbon and oxygen: Determine the equilibrium composition when pure carbon
Isopropyl alcohol is to be dehydrogenated in the gas phase to form propionaldehyde according to the reaction Compute the equilibrium fraction of isopropyl alcohol that would be dehydrogenated at 500
Ionic liquids are salts with melting temperatures that are sufficiently low that they are liquids at or near room temperature. They consist of a larger cation and a smaller anion, for example,
Use the data in problem 8.29 to compute the partial molar enthalpies of pyridine and acetic acid in their mixtures at 25°C over the whole composition range.Problem 8.29Two streams containing
Show that if the polymer fiber of Problem 6.26 is to be thermodynamically stable at all temperatures, the parameters α, β, and γ must be positive.Problem 6.26Nitrogen is to be isothermally
The entropy of a certain fluid has been found to be related to its internal energy and volume in the following way: where S°, U°, and V° are, respectively, the molar entropy, internal energy, and
The heat of fusion ΔfusĤ for the ice-water phase transition is 335 kJ/kg at 0°C and 1 bar. The density of water is 1000 kg/m3 at these conditions, and that of ice is 915 kg/m3. Develop an
From Eqs. 6.2-18 and 6.2-20, we have the following as definitions of the heat capacities at constant volume and constant pressure:More generally, we can define a heat capacity subject to some other
Redo Illustration 7.5-2 using the Soave–RedlichKwong equation of state.Illustration 7.5-2Complete the calculated thermodynamic properties chart for oxygen by considering temperatures between
The sublimation pressure of carbon dioxide as a function of temperature is and the molar volume of CO2 is 2.8 × 10−5 m3/mol. a. Determine the heat of sublimation of CO2 at 190 K. b. Estimate
Use the Analysis>Pure tool in Aspen Plus with the Peng-Robinson equation of state to compute the vapor pressures of the refrigerants R12 (dichlorodifluoromethane, or Freon 12), R124
Redo Problem 6.32 using Aspen PlusProblem 6.32Repeat the calculations of Problem 6.13 if the mechanical efficiency of the adiabatic turbine is only 85 percent.Problem 6.13Eighteen kilograms of the
Redo Problem 6.31 using Aspen PlusProblem 6.31Steam is continuously expanded from a pressure of 25 bar and 300°C to 1 bar through a Joule-Thomson expansion valve. Calculate the final temperature and
Redo Problem 6.29 using Aspen PlusProblem 6.29Nitrogen is to be isothermally compressed at 0°C from 1 bar to 100 bar. Compute the work required for this compression; the change in internal energy,

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