Temperature, conversion factors

Chemical Flowsheet Basic unit operation selection with flow rates, conversion factors, temperatures, pressures, solvents and catalyst selection Process synthesis route Laboratory and pilot scale trials Knowledge of existing processes... 

Whenever necessary, values taken from the literature have been converted into SI units using the appropriate conversion factors. Temperatures are based on the International Temperature Scale of 1990 (ITS-90). The molar quantities are based on the 2005 table of the lUPAC Commission on Atomic Weights and Isotopic Abundances. The standard atomic weights apply to elements as they exist naturally on Earth (natural abundance of the stable nuclides) (06LID1). 

Knowing the conversion factor (temperature rise per unit leak rate), the temperature rise that is associated with Ql is calculated. 

The water-vapor transmission rate (WVTR) is another descriptor of barrier polymers. Strictly, it is not a permeabihty coefficient. The dimensions are quantity times thickness in the numerator and area times a time interval in the denominator. These dimensions do not have a pressure dimension in the denominator as does the permeabihty. Common commercial units for WVTR are (gmil)/(100 in. d). Table 2 contains conversion factors for several common units for WVTR. This text uses the preferred nmol/(m-s). The WVTR describes the rate that water molecules move through a film when one side has a humid environment and the other side is dry. The WVTR is a strong function of temperature because both the water content of the air and the permeabihty are direcdy related to temperature. Eor the WVTR to be useful, the water-vapor pressure difference for the value must be reported. Both these facts are recognized by specifying the relative humidity and temperature for the WVTR value. This enables the user to calculate the water-vapor pressure difference. Eor example, the common conditions are 90% relative humidity (rh) at 37.8°C, which means the pressure difference is 5.89 kPa (44 mm Hg). 

A-l Alphabetical Conversion Factors, 547 A-2 Physical Property Conversion Factors, 371 A-3 Synchronous Speeds, 574 A-4 Conversion Factors, 574 A-5 Temperature Conversion, 577 ... 

A-l Alphabetical Conversion Factors, 416 A-2 Physical Property Conversion Factors, 423 A-3 Synchronous Speeds, 426 A-4 Conversion Factors, 427 A-5 Temperature Conversion, 429 A-6 Altitude and Atmospheric Pressures, 430 A-7 Vapor Pressure Curves, 431 A-8 Pressure Conversion Chart, 432 A-9 Vacuum Conversion, 433 A-10 Decimal and Millimeter Equivalents of Fractions,... 

Strategy The solubility at a particular temperature gives a relationship between grams of sugar and grams of water. This in turn leads to a conversion factor to calculate either the mass of sugar or that of water. 

Most of these conversion factors can be found in Table 1.3. For the temperature conversion, use the relation ... 

Conversion of units from one system to another is simply carried out if the quantities are expressed in terms of the fundamental units of mass, length, time, temperature. Typical conversion factors for the British and metric systems are ... 

The conversion of temperatures is carried out slightly differently. Because the Fahrenheit degree (°F) is smaller than a Celsius degree by a factor of 9 (because there are 180 Fahrenheit degrees between the freezing point and boiling point of water but only 100 Celsius degrees between the same two points) and because 0°C coincides with 32°F, we use... 

Integers and exact numbers In multiplication or division by an integer or an exact number, the uncertainty of the result is determined by the measured value. Some unit conversion factors are defined exactly, even though they are not whole numbers. For example, 1 in. is defined as exactly 2.54 cm and the 273.15 in the conversion between Celsius and Kelvin temperatures is exact so 100.000°C converts into 373.150 K. 

The combination of constants RTIF often appears in electrochemical equations it has the dimensions of voltage. At 25°C (298.15 K) it has a value of 0.02569 V (or roughly 25 mV). When including the conversion factor for changing natural to common logarithms, we find a value of 0.05916 V (about 59 or 60mV) for 2.303 (RTIF) at 25°C. Values for other temperatures can be found by simple conversion, since this parameter is proportional to the absolute temperature. 

Still other units encountered in the literature and workplace come from various other systems (absolute and otherwise). These include metric systems (c.g.s. and MKS), some of whose units overlap with SI units, and those (FPS) based on English units. The Fahrenheit and Rankine temperature scales correspond to the Celsius and Kelvin, respectively. We do not use these other units, but some conversion factors are given in Appendix A. Regardless of the units specified initially, our approach is to convert the input to SI units where necessary, to do the calculations in SI units, and to convert the output to whatever units are desired. 

Autoignition temperature Flashpoint Flammability limits Conversion factors... 

The Saybolt universal viscosity equivalent to a given kinematic viscosity varies slightly with the temperature at which the determination is made because the temperature of the calibrated receiving flask used in the Saybolt method is not the same as that of the oil. Conversion factors are used to convert kinematic viscosity from 2 to 70 cSt at 38°C (100°F) and 99°C (210°F) to equivalent Saybolt universal viscosity in seconds. Appropriate multipliers are listed to convert kinematic viscosity over 70 cSt. For a kinematic viscosity determined at any other temperature, the equivalent Saybolt universal value is calculated by use of the Saybolt equivalent at 38°C (100°F) and a multiplier that varies with the temperature ... 

For chemical reactions and phase transformations, the energy absorbed or liberated is measured as heat. The principal unit for reporting heat is the calorie, which is defined as the energy needed to raise the temperature of 1 gram of water at l4.5° C by a single degree. The term kilocalorie refers to 1,000 calories. Another unit of energy is the joule (rhymes with school), which is equal to 0.239 calories. Conversely, a calorie is 4.184 joules. The translation of calories to joules, or kilocalories to kilojoules, is so common in chemical calculations that you should memorize the conversion factors. 

Before you start your hooray-chemistry-is-finally-getting-simple dance, understand that certain conditions apply to this conversion factor. For example, it s true only at standard temperature and pressure (STP), or 0°C and 1 atmosphere. Also, the figure of 22.4 L/mol applies only to the extent that a gas resembles an ideal gas, one whose particles have zero volume and neither attract nor repel one another. Ultimately, no gas is truly ideal, but many are so close to being so that the 22.4 L/mol conversion is very useful. 

In equation (18.1), E1 is the standard potential and is a constant that includes all other potentials, R is the ideal gas constant, T is the temperature, z is the charge carried by ion i to be measured and whose activity is a, F represents Faraday s constant and 2.303 is the logarithmic conversion factor. 

Karweil (12) tried to illustrate graphically the correlation between coal rank, rock temperature, and duration of heating on the basis of reaction kinetics. In Figure 18 the ordinate records the temperature, and the abscissa indicates coal rank (in terms of volatile matter and a conversion factor = Z). 

Figure 18. Relations between rank of coal (volatile matter), temperature, and time of coalification (after Karweil (12)) (Z is a conversion factor relating volatile matter to coal rank)...

In modern industrial ethyl alcohol plants, the compound is produced in two principal ways (I) by direct hydration of ethylene, or (2) by indirect hydration of ethylene. In the direct hydratiun process. H 0 is added to ethylene in the vapor phase in Lhe presence of a catalyst CH CH 4- H 0 CHiCHiOH. A supported acid catalyst usually is Used. Important factors affecting the conversion include temperature, pressure, the H 0/CH CH ratio, and the purity of (he ethylene, Further, some byproducts are formed by other reactions taking place, a primary side reaction being the dehydration of ethyl alcohol into diethyl ether 2C HjOH (C Hs)jO + HiO. To overcome these problems, a large... 

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