For the elementary gas phase reaction H+C2H4 ®C2H5, the second-order rate constant
varies with temperature in the following way:
T / K 198 298 400 511 604
1012 k/(cm3molecule-1s-1) 0.20 1.13 2.83 4.27 7.69
a) Use the data to calculate the activation energy, Ea, and the pre-exponential factor, A, for the reaction.
b) The simple collision theory of bimolecular reactions yields the following expression for the rate constant:
k = (8kT/p m)1/2 sexp(-Ea/RT)
where mis the reduced mass of the reactants and s is the reaction cross section.
i) Interpret the role of the three factors in this expression.
ii) Use the answer to part a) to estimate s for the reaction at 400K.
iii) Compare the value obtained with an estimate of 4.0x10-19 m2 for the collision cross section.
[Take the atomic masses of H and C to be 1.0 amu and 12 amu, respectively.]
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Below is a list of examples of benefits that ecosystems provide to people. Match each benefit with the correct category of ecosystem services.
| A. Regulating services |
| B. Provisioning services |
| C. Supporting services |
| D. Cultural services |
| selectABCD | 1. Before Europeans came, Michigan had a large area of old growth beech-maple forest near its southern border. Except for a small area where the loggers ate lunch, the entire beech-maple forest ecosystem was logged in the 1800’s. Only the loggers’ picnic area remains as a small remnant (~300 acres) of the great beech-maple forest. That remnant is now called Warren Woods. The ancient beech trees in Warren Woods are about 125 feet tall. The soil is rich, and the ground is covered with colorful wildflowers. For many years, a sign at the entrance stated, “Welcome to the forest primeval.” People come to experience walking through an ancient forest that feels like a cathedral. |
| selectABCD | 2. Since about 3 billion years ago, miniscule aquatic bacteria have been performing photosynthesis, releasing oxygen as a byproduct. They and their descendants, called chloroplasts, which live inside the cells of algae and land plants, produced, and continue to produce, nearly all the oxygen in our atmosphere. They also capture carbon from the atmosphere and incorporate it into carbohydrates, fats, oils, protein, and other types of food. All the carbon in all of our foods came to us by way of these photosynthetic bacteria and their descendants. |
| selectABCD | 3. The dead remains of leaves, insects, worms, and other organisms contain thousands of different kinds of organic (carbon-containing) and inorganic chemicals. Plants are unable to use these chemicals until the dead remains are chemically transformed during the decay process. Decay is carried out by various types of fungi, bacteria, and other microorganisms. Without the chemical transformations that take place during the decay process, living plants would quickly use up all the available nutrients in the soil and die. Without decay, there would be no plants. Without plants, there would be no animals. |
| selectABCD | 4. Large lakes are fed by incoming streams. When the forest is intact, the streams are deep and the water is cold and clear. Fish and other animals do better in cold water because cold water can hold more oxygen. The presence of the lake also causes a moderation in the air temperature near the lake. |
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A vertical vessel with an internal diameter of 84” has a hemispherical head at the top and an ellipsoidal head of 2:1 at the bottom. The construction material has a maximum allowable stress of 8700 psi at its design temperature. The operating pressure is stated as 48 psig. The overall height of the vessel is 38‟ and a joint efficiency of 1.0 is used.
) Determine the wall thickness of each part of the vessel.
b) If a corrosion allowance of 2 mm is being fixed by the user, determine the wall thicknesses and part MAWPs for each part of the vessel and what is the vessel MAWP?
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.Define the terrestrial age of a meteorite and explain, in your own words, how this is determined. (About 200 words)
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give your theory or idea on why time is 24 hours, why are their 60 minute's in an hour and 60 seconds in a minute. Why did early civilizations pick these particular numbers for time. Give your response with a paragraph explaining your theory, idea and or argument.
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Describe how humans have affected the numerous pathways and reservoirs in the carbon cycle that have contributed to climate change. Find three examples where positive feedback in the environment is likely contributing more carbon dioxide to the atmosphere that is not a result of human activities.
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Discuss the factors contributing to Antarctica’s extreme cold. Discuss why Antarctica is significant to studying global climate change. Discuss the changes of Alpine glaciers and their causes.
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(a) Tobaco Berhad, with the Ringgit Malaysia as its functional currency, purchases plant from a foreign entity for $18 million on 31 May 2019 when the exchange rate was $2 to RM1. The entity also sells goods to a foreign customer for $10.5million on 30 September 2019, when the exchange rate was $1.75 to RM1. At the entity’s year end of 31 December 2019, both amounts are still outstanding and have not been paid. The closing exchange rate was$1.5 to RM1. Required: Explain the accounting treatment for both sale and purchases transactions for Tobacco Berhad.
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what is the difference between bin, silo, and hopper in solid handling? is there any size limit to each of them? and could you please provide me with reference (preferably textbook)
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1. A steam turbine operates adiabatically with a steam rate of 25 kg/s. The steam is supplied at 300 kPA and 400 oC and discharged at 40 kPA and 100 oC. Use steam tables to solve this problem.
a. Determine the power output of the turbine.
b. Determine the power output of turbine for reversible process.
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What could be the national/global, economic, cultural, managerial-organisational legal, societal and political impacts of a macro project that aims to break down oxygen and water from the moon crest and bring the same to the earth surface.
In conjunction with this research and development, the project also focus on creating a livable space station in moon for refueling the spaceships travelling from earth to moon & back to earth. What is the best marketing plan and public relations strategy for this project.?
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Methanol is produced by reacting carbon monoxide and hydrogen. A fresh feed stream containing CO and H2 joins a recycle stream and the combined stream is fed to a reactor. The reactor outlet stream flows at a rate of 350 mole/min and contains 10.6 wt% H2 , 64 wt% CO and 25.4 wt% CH3OH. This stream enters a cooler in which most of the methanol is condensed. The liquid methanol condensate is withdrawn as a product, and the gas stream leaving the condenser – which contains CO, H2 and 0.4 mole % uncondensed CH3OH vapor – is the recycle stream that combines with the fresh feed. Determine a) the molar flow rates of CO and H2 in the fresh feed b) the production rate of liquid methanol (mol/min) and c) the molar flow rate of the recycle stream.
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What percentage of the earth’s water is fresh water?
Why is it such a big problem to be cycling massive and growing volumes of grains and oil- seeds through livestock?
What are overrides? Use examples from the chapter.
Why are antibiotics used in animal feed, and why is this problematic?
Fundamental imbalances in the distribution of the world’s food supply is caused by cycling humanly edible grains and oilseeds through animals to produce flesh, eggs, and milk, destroying much more protein and other usable plant nutrition than it contributes to human societies (111). Explain.
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