Pressure, atmospheric volume-mass-temperature

Input is balanced by output in a steady-state system. The concentration of an element in seawater remains constant if it is added to the sea at the same rate that it is removed from the ocean water by sedimentation. Input into the oceans consists primarily of (1) dissolved and particulate matter carried by streams, (2) volcanic hot spring and basalt material introduced directly, and (3) atmospheric inputs. Often the latter two processes can be neglected in the mass balance. Output is primarily by sedimentation occasionally, emission into the atmosphere may have to be considered. Note that the system considered is a single box model of the sea, that is, an ocean of constant volume, constant temperature and pressure, and uniform composition. 

Because the gas s mass is given, we choose the expanded form of the ideal gas equation. We rearrange the equation to isolate the unknown volume, plug in given values, and cancel our units. In order to cancel the pressure and volume units, we must convert 952 mmHg into atmospheres and convert 23.0 mL into liters. When this is done, the units cancel to yield an answer in kelvins. Because kelvin is a reasonable temperature unit, we can assume that we have picked the correct equation, done the algebraic manipulation correctly, and made all of the necessary unit conversions. 

Our intent is to apply the first law of thermodynamics to an air parcel whose volume is changing as it either ascends or descends in the atmosphere. Ultimately we will combine our result with (1.3), and so it is more convenient to work with pressure and temperature as the variables rather than with pressure and volume. Thus we convert pdV to a. form involving p and T. To do this, we express the ideal gas law as pV = mRT/M. r for a mass m of air. Then... 

Humidity is generally expressed as relative humidity and quoted as a percentage. It is the ratio at a given atmospheric temperature and pressure of the mass of water in a given volume of air to the mass if the air had been saturated with water. (See Table 18.2.)... 

Density is the mass per unit volume kg m b The density of a fluid depends on temperature and on atmospheric pressure or a static imposed head. At stan dard conditions 20 °C and 101.325 kPa (atmospheric pressure at sea level)... 

A group of chemistry students have injected 46.2 g of a gas into an evacuated, constant-volume container at 27°C and atmospheric pressure. Now the students want to heat the gas at constant pressure by allowing some of the gas to escape during the heating. What mass of gas must be released if the temperature is raised to 327°C ... 

The density of a material is a function of temperature and pressure but its value at some standard condition (for example, 293.15 K or 298.15 K at either atmospheric pressure or at the vapor pressure of the compound) often is used to characterize a compound and to ascertain its purity. Accurate density measurements as a function of temperature are important for custody transfer of materials when the volume of the material transferred at a specific temperature is known but contracts specify the mass of material transferred. Engineering applications utilize the density of a substance widely, frequently for the efficient design and safe operation of chemical plants and equipment. The density and the vapor pressure are the most often-quoted properties of a substance, and the properties most often required for prediction of other properties of the substance. In this volume, we do not report the density of gases, but rather the densities of solids as a function of temperature at atmospheric pressure and the densities of liquids either at atmospheric pressure or along the saturation line up to the critical temperature. 

In this equation, u is the osmotic pressure in atmospheres, n is the number of moles of solute, R is the ideal gas constant (0.0821 Latm/K mol), T is the Kelvin temperature, V is the volume of the solution and i is the van t Hoff factor. If one knows the moles of solute and the volume in liters, n/V may be replaced by the molarity, M. It is possible to calculate the molar mass of a solute from osmotic pressure measurements. This is especially useful in the determination of the molar mass of large molecules such as proteins. 

The processor was operated at atmospheric pressure and at 117—130 °C or 200 °C. A methanol-water mixture (1 1.5 molar ratio) was fed at 0.1 cm /h using a syringe pump. The reactors loaded with powder and pellets had comparable results, but the researchers preferred the powder packed bed form for its smaller volume and mass. The best hydrogen production was obtained at low temperatures, providing, on a dry gas basis, 70% hydrogen, 0.5% carbon monoxide, and residual carbon dioxide. Methanol conversion or thermal efficiency was not reported. 

Find the pressure and temperature of each state of an ideal Diesel cycle with a compression ratio of 15 and a cut-off ratio of 2. The cylinder volume before compression is 0.16 ft. The atmosphere conditions are 14.7 psia and 70°F. Also determine the mass of air in the cylinder, heat supplied, net work produced, MEP, and cycle efficiency. 

Determine the temperature at the end of the eompression proeess, compression work, expansion work, and thermal efficiency of an Otto Miller cycle. The volumes of the cylinder before and after compression are 3 liters and 0.3 liter. Heat added to the air in the combustion chamber is 800kJ/kg. A supercharger and an intercooler are used. The supercharger pressure is 180 kPa and the temperature at the end of the intercooler is 20°C. The intake valve closes at 2.8 liters. The end temperature of the cooling process of the cycle is 20°C. What is the mass of air in the cylinder The atmosphere conditions are 101.3 kPa and 20° C. 

The concentration in air, however, is typically given in units that are different from those of water, because mass per unit volume can be misleading in a media that can be signihcantly compressed. Thus, concentration in the atmosphere is often given as a partial pressure at one atmosphere of total pressure. Because the pressure of a gas at a given temperature is proportional to the number of molecules in a given volume, the following relations are applied ... 

Mass of ampoule, g Ditto, with liquid being tested, g Mass of liquid being tested, g Volume of displaced air, litre Atmospheric pressure, mmHg Temperature, °C... 

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