Explore BrainMass

Molecular Engineering

Molecular engineering studies molecules that are used to create new molecules which may not exist in nature. This process is difficult requiring manual manipulation of molecules using such devices as a scanning tunneling microscope. It is expected that eventually to exploit lifelike self-replication ‘helper molecules’ that are themselves engineered. Therefore, the field can be seen as a precision form of chemical engineering.

Molecular engineering is an important aspect of pharmaceutical research and materials science. The advent of the scanning tunneling microscope and picosecond-burst lasers in the 1990s, plus discovery of new carbon nanotube applications to motivate mass production of these custom molecules which drove the field forward to commercial reality in the 2000s. Future developments in molecular engineering hold out the promise of great benefits, as well as risks. Nanotechnology discussions spark more controversy in the fields of science and engineering.

Reactant (Limiting and excess)

A problem has been attached concerning a rector problem and the limiting reactant and excess reactant. I have some idea how to approach the problem, but would like confirmation. Please include work and explanation. Thx.

Mixture of Perfect Gases

A mixture of perfect gases consist of 3kg of carbon monoxide and 1.5kg of nitrogen at a pressure of 0.1 MPa and a temperature of 298.15 K. Using table 5-1, find: a) the effective molecular mass of the mixture b) its gas constant c) specific heat ratio d) partial pressures e) density Please see the attachment for a comple

Stoichiometry of Ammonia Synthesis

Show that the maximum concentration of NH3 is obtained in an ammonia synthesis process when the ratio of nitrogen to hydrogen is 1:3, provided that the gas mixture may be assumed to be perfect. The reaction is:

Volume of Air Required for Combustion of a Natural Gas Mixture

A natural gas has the following analysis by volume: Methane (ch4) 87%, hydrogen 5% and nitrogen 8%. Determine: A) The minimum volume of air necessary for the complete combustion of 1 m3 of the gas. B) The volumetric analysis of the exhaust gases if 20% excess air is supplied.

Mass of Air Required for Combustion of Fuel

A coal fired boiler uses fuel having the following analysis by mass: Carbon 81%, hydrogen 5%, oxygen 6 %, ash 8%. A) Determine the minimum mass of air necessary for complete combustion of 1 kg of fuel. B) If 40% excess air is supplied, determine the percentage composition of the dry exhaust gases by mass.

Continuous Stirred Tank Reactor (CSTR):Flow rate and Reactor Volume

The liquid phase reactions a. A+B--->C b. A+B--->D are carried out in a perfectly insulated CSTR. The desired reaction (a) is first order in A and zero order in B, while the undesired reaction (b) is zero order in A and first order in B. The feed rate is equimolar in A and B. Species A enters the reactor at a temperatu

Material balances for combustion of octane

One of the most common chemical reactors found around us is the car engine. It takes gasoline and reacts it with air to release chemical energy, which in turn is transformed into mechanical energy. Emissions from your car's engine have been an environmental concern for many years. Using the concepts of material balances,

Weight Percentage of MTBE (methyl tert-butylether) in Gasoline : Oxygen Content

If gasoline had a hypothetical chemical formula of C8H17, and we knew the chemical formula of MTBE as CH3OC4H9, what weight (actual weight and percent by weight) of MTBE should be in the gasoline to achieve a final gasoline blend that has 2.7% oxygen by weight? Assume the densities of gasoline and MTBE equivalent at 0.75 g per c

BOD of Algae

Large blooms of algae result from high nutrient loading in rivers and lakes, for example, as a result of runoff of fertilizers from agricultural fields. When the algae die, they biodegrade and consume oxygen. The amount of oxygen consumed is called the biochemical oxygen demand (BOD). If the level of oxygen dissolved in water be

Mass and Energy Transfer

If we approximate the atmosphere to be 79% nitrogen (N_2) by volume and 21% oxygen (O_2), estimate the density of air (kg/m^3) at STP conditions (0 degrees C, 1 atm)

Gas Absorption and Transfer Operations: Column Diameter Calculation

A gas absorption column to handle 3630 kg/hr of a gas is being designed. Based on pressure drop, entrainment and foaming considerations, the maximum vapor velocity must not exceed 0.61 meters/sec. If the density of the vapor is 0.801 kg/m^3, what is the column diameter?

If a 22450lb (total gross weight) airplane develops 8160lbf thrust...

1) If a 22450lb (total gross weight) airplane develops 8160lbf thrust from each of its two engines and has a wing area of 312ft2 and wing-span of 53.5ft. And a empty weight of 11770lbf. Determine the thrust to weight ratio and the wing loading of this aircraft? 2) Consider an ordinary, helium-filled party balloon with a volu

Combustion Reactions- Thermochemistry

1. A constant-volume tank consists of a mixture of 120 grams of methane (CH4) gas and 600 grams of O2 at 25 degrees C and 200 kPa. The contents of the tank are now ignited, and the methane gas burns completely. If the final temperature is 1200K, determine (a) the final pressure in the tank, (b) the dry analysis of the product st

Combustion of Ethane: Stack Gas Molar Composition

Ethane is burned with 50% excess air. The percentage conversion of ethane is 90%. Of the ethane burned, 25% reacts to form CO and the balance reacts to form carbon dioxide. Calculate the molar composition of the stack gas on a dry basis, and the mole ratio of water to dry stack gas.

Van Laar equation to calculate activity coefficients

How do I use the Van Laar equation to calculate an activity coefficient for an equilibrium ethanol/water binary system with mole fractions of ethanol in liquid of: 0, 0.05, 0.1, 0.15, 0.2, 0.4, 0.6, 0.8, and 1? I'm looking at the Van Laar equation in Perry's Handbook where A12 is 1.6798 and A21 is 0.9227. I don't understand what

PFR and CSTR in Parallel

Please see the attached file for the fully formatted problem(s). An elementary liquid phase reaction (irreversible first order) A ---> R, takes place in a PFR and the conversion is 96%. If a mixed flow reactor of 10 times as large as the PFR is hooked up in parallel with the existing unit, by what fraction could the productio

Rate Equation from PFR (Pluf Flow Reactor) Data

Please see the attached file for the fully formatted problem(s). Problem: The following conversion data were obtained in a tubular flow reactor for the gas-phase pyrolysis of acetone at 520 oC and 1 atm. CH3COCH3 ---> CH2=C=O + CH4 Flow rate, g/hr 130 50 21 10.8 Conversion of acetone 0.05 0.13 0.24 0.35

Kinetics from CSTR Data

Problem. The kinetics of an aqueous phase decomposition of A is investigated in two CSTR's in series, the first having half the volume of the second. At steady state with a feed concentration of 4 gmol/lit., and mean residence time of 65 sec in the second reactor, the concentration of feed to second from the first is found to b

Mixed Reactors in Series

Please see the attached file for the fully formatted problem(s). Acetic acid is hydrolyzed in three stirred tank reactors operated in series. The feed flows to the first reactor (V = 1 lit) at a rate of 400 cm3/min. The second and third reactors have volumes of 2 and 1.5 liters respectively. The first order irreversible rate

Half Life Method: Example Problem

Problem: The thermal decomposition of nitrous oxide (N2O) in the gas phase at 1030oK is studied in a constant volume vessel at various initial pressures of N2O. The half-life data so obtained are as follows: po (mm Hg) 52.5 139 290 360 t1/2 (sec) 860 470 255 212 2N_2O → 2N_2 + O_2 Determine the r

Distillation and Reflux: Ponchon-Savarit Method

1000 kg/hr of a mixture containing 42 mole percent heptane and 58 mole percent ethyl benzene is to be fractionated to a distillate containing 97 mole percent heptane and a residue containing 99 mole percent ethyl benzene using a total condenser and feed at its saturated liquid condition. The enthalpy-concentration data for the h

Number of Plates at Total Reflux

Problem: A mixture of benzene and toluene containing 40 mole % of benzene is to be separated to give a product of 90 mole % of benzene at the top and bottom product with not more than 10 mole % of benzene. Using an average value of 2.4 for the volatility of benzene relative to toluene, calculate the number of theoretical plates

Differential Distillation: Rayleigh's Equation

Please see the attached file for the fully formatted problem(s). A liquid feed consisting of 1200 gmoles of mixture containing 30% naphthalene and 70% dipropylene glycol is differentially distilled at 100 mm Hg pressure and final distillate contains 55% of the feed solution. The VLE data are x 8.4 11.6 28.0 50.6 68.7 80.6 8

Differential Distillation Benzene and Toluene Separation: Rayleigh's Equation

Please see the attached file for the fully formatted problem(s). 100 moles of Benzene (A) and Toluene mixture containing 50% (mole) of Benzene is subjected to a differential distillation at atmospheric pressure till the composition of benzene in the residue is 33%. Calculate the total moles of the mixture distilled. Average

Differential Distillation by Rayleigh Equation

Problem: A binary mixture of benzene and toluene containing 40% of benzene is to be distilled at 1 atm pressure to recover 95% of the benzene. Estimate the molal percent of mixture to be distilled and the composition of the distillate obtained if distillation is carried out by Differential distillation, collecting all the disti

Equilibrium Flash Distillation

A feed of 50 mole % hexane and 50 mole % octane is fed into a pipe still through a pressure reducing valve and then into a flash disengaging chamber. The vapor and liquid leaving the chamber are assumed to be in equilibrium. If the fraction of the feed converted to the vapor is 0.5, find the compositions of the top and bottom pr

Steam Distillation: Boiling Point Calculation

The problem is attached in the following file. Vapor pressures of chlorobenzene and water are given below: Pressure, mm Hg 100 50 30 26 Temperature oC, Chlorobenzene 70.4 53.7 42.7 34.5 Temperature oC, Water 51.7 38.5 29.9 22.5 If steam is blown into the still containing a mixture of these two components and the total pr

McCabe-Thiele Method: Calculation of Theoretical Plates

The solution is detailed and well presented. Problem: A saturated liquid mixture containing 60 mole % benzene and 40 mole % toluene is to be distilled continuously into a distillate product containing 90 mole % benzene and the bottom product containing 5 mole % benzene. The fractional distillation column will operate at ap