The counts per second (cps) changes when the spot size is changed. Why?

The counts per second (cps) also changes when kV is changed. Why?

In general, which parameter would you change, spot size or kV, to increase the counts per second? Why?

This is when using an Scanning Electron Microscopy (SEM) or Energy Dispersive Spectroscopy (EDS).

Two kilograms of CO₂ gas is contained in a piston-cylinder assembly at a pressure of 6.5 bar and a temperature of 300 K. The piston has a mass of 5000 kg and surface area of 1m². The friction of the piston on the walls is significant and cannot be ignored. The atmospheric pressure is 1.01325 bar. The latch holding the piston in position is suddenly removed and the gas is allowed to expand. The expansion is arrested when the volume is double the original volume. Determine the work appearing in the surroundings. Will it be the same as the work done by the gas?

PROBLEM: Ammonia is used as a refrigerant. It is compressed outdoors, and the ammonia is then liquefied and circulated through the refrigerator's evaporator heat exchanger. The evaporator is indoors. The room containing the evaporator has a net open volume of 1000 m3 and a ventilation rate equal to two air changes per hour. A leak develops in an ammonia line that results in 50 g of ammonia being released per minute. 1. How long will it take for the ammonia concentration to increase to the PEL concentration? 2. How long will it take to reach the IDLH concentration? 3. If the flow of ammonia is stopped at the time the IDLH concentration is reached, how long will it be before the concentration is reduced to the PEL concentration? You may assume that the mixtures of gases are ideal at the low pressures involved. Also assume that the ammonia is mixed with the air in the room completely and instantaneously and that the air- ammonia mixture leaving the room has the same concentration as the mixture in the room. Hint: Use a differential equation and separation of variables to solve.

4 (a) Derive a relation for the oxygen pressure dependence of electrical conductivity in NiO.
(b) Discuss the effects of Cr2O3 additions on the electrical conductivity of NiO, giving equations describing the temperature at which the conductivity changes from intrinsic to extrinsic in relation to the impurity concentration.

For a 10m diameter reactor full of spherical iron beads (r=1.5cm), the minimum height for fluidization is 50m, and the minimum porosity is 0.1. The volumetric flow rate is controlled and kept at 0.5L/s. For which fluids listed below will the reactor act as a packed bed and which will act as a fluidized bed? Assume laminar flow.

Ethylene glycol

Silicone oil

Bromine

Acetone

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Discuss the following in detail:

(1) Equimolar counterdiffusion and unimolecular diffusion in liquids

(2) For diffusion in liquids between counterdiffusion and unimolecular diffusion which is more commonly observed? Why is this observed?

A vapor composed of 0.65 mole fraction ethanol and 0.35 mole fraction acetic acid at 120.0 mmHg (absolute), is in equilibrium with a liquid phase also composed of ethanol and acetic acid. Assume that the liquid is an ideal solution and apply Raoult's law to find the following.

What is the temperature of the liquid____^oC?

What are the mole fractions of the liquid pahse?

X_E=___mol ethanol/mol

X_A=___ mol acetic acid/mol

Consider a spherical tank of air originally at atmospheric pressure (1.013*105 N/m2). Air is being supplied at a uniform velocity of 2 m/s through a tube of diameter 2 cm. The tanks diameter is 1m. The inlet pressure is maintained at 3*105 N/m2 and the temperature of the tank and inlet pipe is 300K. Determine the time required for the pressure in the tank to reach 2*105 N/m2.

Please make sure to display your thought process? It is important to be able how the answer was deduced.

A certain extruder for plastics was found to work best at a melt viscosity of 2 X 10⁴ Pa-s. The polymer of choice had this viscosity at 145 °C when its DP­_w was 700. This polymer has a Tg of 75 °C. Because of polymerization kinetics miscalculation by someone who did not take polymer science, today’s polymer has DP_w of 500. At what temperature should the extruder be run so that the viscosity will remain at optimum conditions? (Assume two carbon atoms per mer backbone)

Calculate the energy required to convert 100 kg of ice at 0 degrees C and 1 atm. to water vapor at 650 degrees C and 60 bar. The heat of fusion of ice is 333.6 J/g at 0 degrees C.

Suggested path: i) convert the ice from solid to liquid, ii) heat the liquid to the boiling point, iii) convert the saturated liquid to a saturated vapor, iv) heat the vapor to the final temperature, v) pressurize the gas to the final pressure. Other paths are equally effective.

1. What are the main differences between the production of oil, natural gas and coal?

2. Write a short description of Gas to refinery products (fuels) conversion technology using Natural gas, carbon dioxide and water?

Which form of biomass do you prefer and why?

Consider the materials used for a bicycle frame. Common materials are aluminum, titanium and steel. A) Explain what are the main considerations for material selection for this application. B) Mention the principal advantages and disadvantages of using the mentioned materials. C) How can advanced materials can be used in this application? Which advanced materials do you propose that can be used?

A natural gas containing 82 mol% CH4 and the balance C2H6 is burned with 25% excess air in a boiler furnace. The fuel gas enters the furnace at 298 K, and the air is preheated to 423 K. The heat capacities of the stack gas components may be assumed to have the following constant values:

CO2: Cp=50.0 J/(mol.K)

H2O(v): Cp=38.5 J/(mol.K)

O2: Cp=33.1 J/(mol.K)

N2: Cp=31.3 J/(mol.K)

Assuming complete combustion of the fuel, calculate the adiabatic flame temperature in K.