SI units temperature

TABLE 2-352 Saturated Water Substance—Temperature (SI units)... 

There are seven base SI units including the kilogram (for mass) and the kelvin (for temperature). SI units for such quantities as volume and density are derived from the base units. 

Temperature SI Unit Kelvin (K) Pressure SI Unit Pascal (Pa) Energy SI Unit Joule (J)... 

FIGURE 2 12 Boiling points of unbranched alkanes and their 2 methyl branched iso mers (Temperatures in this text are expressed in de grees Celsius C The SI unit of temperature is the kelvin K To convert degrees Celsius to kelvins add 273 15 )... 

The SI unit of viscosity is pascal-second (Pa s) or newton-second per meter squared (N s m ). Values tabulated are mN s (= centipoise, cP). The temperature in degrees Celsius at which the viscosity of a... 

The dynamic viscosity, or coefficient of viscosity, 77 of a Newtonian fluid is defined as the force per unit area necessary to maintain a unit velocity gradient at right angles to the direction of flow between two parallel planes a unit distance apart. The SI unit is pascal-second or newton-second per meter squared [N s m ]. The c.g.s. unit of viscosity is the poise [P] 1 cP = 1 mN s m . The dynamic viscosity decreases with the temperature approximately according to the equation log rj = A + BIT. Values of A and B for a large number of liquids are given by Barrer, Trans. Faraday Soc. 39 48 (1943). 

Temperature. The kelvin is the SI unit of thermodynamic temperature, and is generally used in scientific calculations. Wide use is made of the degree Celsius (°C) for both temperature and temperature interval. The temperature interval 1°C equals 1 K exacdy. Celsius temperature, t, is related to thermodynamic temperature, T, by the following equation ... 

Viscosity. Although traditionally of Httle importance in the evaluation of vegetable and insect waxes, viscosity is an important test for mineral and synthetic waxes. One of the most frequently used tests, ASTM D88, is used to measure the time in seconds required for a specified quantity of wax at a specified temperature to flow by gravity through an orifice of specified dimensions. This viscosity is expressed in Saybolt Universal Seconds (SUS) at the temperature of the test. The SI unit for kinematic viscosity is mm /s (=cSt). 

The solubihty coefficient must have units that are consistent with equation 3. In the hterature S has units cc(STP)/(cm atm), where cc(STP) is a molar unit for absorbed permeant (nominally cubic centimeters of gas at standard temperature and pressure) and cm is a volume of polymer. When these units are multiphed by an equihbrium pressure of permeant, concentration units result. In preferred SI units, S has units of nmol /(m GPa). 

Unpublished data of General Chemicals Division, Allied Chemical Company. Used by permission, c = critical temperature. No material in SI units appears in the 1993 ASHRAE Handbook—Fundamentals (SI ed.). Tables and a chart to 50 ata, 200 C are given by Mathias, H. and H. J. Loffler, Techn. Univ. Berhn rept., 1966 (42 pp.). A chart to 1500 psia, 500 F was given by Mears, W. H., E. Rosenthal, et al.,y, Chem. Eng. Data, 11, 3 (1966) 338-. l43. 

The Iduematic viscosity (v) is defined as the ratio of the absolute viscosity to density at the same temperature and pressure. The most common unit corresponding to the poise is the stoke (1 cmVsec). The SI unit would be mVsec. 

This example will use only SI units, except that pressure will be in atm, not kPa. Flue gas containing 6 percent CO9 and 11 percent H9O vapor, wet basis, flows tbroiigb a bank of tubes of 0.1016 in (4-in) outside diameter on equilateral 0.2032 m (8-in) triangular centers. In a section in wbicb the gas and tube surface temperatures are 691 C (964 K) and 413 C (686 K), what are the emissivity and absorptivity of the gas From Table 5-8, = (2.8)(0.01016) = 0.2845 m (only SI... 

Tr = temperature of reactants at relief set pressure To = aUowable temperature following complete quench To = initial temperature of the quen fluid = specific heat of the quench fluid Cr = specific heat of the reac tants (consistent Enghsh or SI units)... 

It is usual these days to express all physical quantities in the system of units referred to as the Systeme International, SI for short. The International Unions of Pure and Applied Physics, and of Pure and Applied Chemistry both recommend SI units. The units are based on the metre, kilogram, second and the ampere as the fundamental units of length, mass, time and electric current. (There are three other fundamental units in SI, the kelvin, mole and candela which are the units of thermodynamic temperature, amount of substance and luminous intensity, respectively.)... 

In this book, we will express our thermodynamic quantities in SI units as much as possible. Thus, length will be expressed in meters (m), mass in kilograms (kg), time in seconds (s), temperature in Kelvins (K), electric current in amperes (A), amount in moles (mol), and luminous intensity in candella (cd). Related units are cubic meters (m3) for volume, Pascals (Pa) for pressure. Joules (J) for energy, and Newtons (N) for force. The gas constant R in SI units has the value of 8.314510 J K l - mol-1, and this is the value we will use almost exclusively in our calculations. 

Table A4.1 Thermodynamic functions of an ideal gas. (Use R = 8.314510 J-K l mol 1 and SI units for pressure, temperature, and all molecular data.)...

Prior to the now almost universal adoption of the SI system of units, the unit of heat was defined as the quantity of heat required to raise the temperature of unit mass of water by one degree. This heat quantity is designated the calorie in the cgs system and the kilocalorie in the mks system, and in both cases temperature is expressed in degrees Celsius (Centigrade). As the specific heat capacity is a function of temperature, it has been necessary to set a datum temperature which is chosen as 298 K or 25°C. 

The constant R is called the gas constant and has the same value for all gases because R is independent of the identity of the gas, we say that it is a universal constant. The value of the gas constant can be found by measuring P, V, n, and T and substituting their values into R = PV/nT. When we use SI units (pressure in pascals, volume in meters cubed, temperature in kelvins, and amount in moles),... 

Kekule structures Two Lewis structures of benzene, consisting of alternating single and double bonds, kelvin (K) The SI unit of temperature. See also Appendix IB. 

Kelvin scale A fundamental scale of temperature on which the triple point of water lies at 273.16 K and the lowest attainable temperature is at 0. The unit on the Kelvin scale is the kelvin, K. ketone An organic compound containing a carbonyl group between two carbon atoms, having the form R—CO R. Example CH3—CO—CH2CH , butanone. kilogram (kg) The SI unit of mass. See also Appendix IB. 

In this equation, T is the temperature in kelvins, is Avogadro s number (units of molecules/mol), and R is the gas constant. For energy calculations, we express R in SI units, which gives kinetic energy in joules per molecule. The value of R in SI units is i = 8.314 J mol K ... 

The amount of heat released by the complete combustion of one mole of a substance is defined as the heat of combustion, AAVcomb The amount of heat released may be measured in calories (cal) or in joules (J). A calorie is the amount of heat needed to raise the temperature of one gram of water one degree Celsius. The SI unit of heat is the joule. One joule is equal to 4.184 calories. 

Mean heat capacities for the combustion gases are readily available in handbooks and texts on heat and material balances. The following values are taken from K. A. Kobe, Thermochemistry of Petrochemicals, reprint No. 44, Pet. Ref. 1958 converted to SI units, J/mol°C, reference temperature 0°C. 

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