Temperatures scales, converting

Converting between Celsius (°C) and Kelvin (K) temperature scales Converting between Celsius (°C) and Fahrenheit (°F) temperature scales Definition of density... 

EXAMPLE 3.7 Converting between Celsius and Kelvin Temperature Scales Convert -25 °C to kelvins. ... 

EXAMPLE 3.8 Converting between Fahrenheit and Celsius Temperature Scales Convert 55 °F to Celsius. ... 

The Kelvin temperature scale is defined to have the freezing point of pure water at 273.15 K and the normal boiling point of pure water at 373.15 K. The unit of the Kelvin temperature scale is the kelvin. (We do not use degrees with Kelvin.) Thus, its temperatures are essentially 273° higher than the same temperatures on the Celsius scale. To convert from Celsius to Kelvin, merely add 273° to the Celsius temperature. To convert in the opposite direction, subtract 273° from the Kelvin temperature to get the Celsius equivalent. (See Fig. 2-2.)... 

EXAMPLE 2.47. Convert 0°C and 10°C to Kelvin. Calculate the change in temperature from 0°C to 10°C on both temperature scales. 

A temperature scale widely used in the US industry. On this scale 32° is the freezing point of water and 212° the boiling point. See Celsius. To convert x°F to y°C ... 

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. 

Know how to convert from any one of the Fahrenheit/Celsius/Kelvin temperature scales to the other two. 

When converting to the absolute temperature scale T, it is important to recognize the convention 0°C — 273.15 K. The constants A and B in Eq. (3) are determined empirically from experimental data by plotting log P versus 1 /T and taking the slope as —A and the intercept at 1/T = 0 as B. Equation (2) is found to yield a fairly accurate fit to vapor pressure data for highly volatile substances and is often perfectly adequate for moderately accurate data below the boiling point. 

Oil Shale (Shale Oil) Sedimentary rock that contains kerogen, a solid, waxy mixture of hydrocarbon compounds. Heating the rock to very high temperatures will convert the kerogen to a vapor, which can then be condensed to form a slow flowing heavy oil that can later be refined or used for commercial purposes. The United States contains vast amounts of oil shale deposits, but so far it has been considered not economically feasible to produce from them on a large scale. 

What are the three temperature scales Can you convert between them ... 

A platinum-10% rhodium to platinum thermocouple was operated with hot and cold junctions, respectively, in the alloy and condensed cadmium regions. Reference tables (16) were used to convert e.m.f. to absolute temperature. However, in the tables, temperatures are rounded to the nearest 0.1° C., which is too rough for our temperature differences. The tables are based on earlier work (13) with the values adjusted to the 1948 international temperature scale. To evaluate the difference between alloy and cadmium condensate temperatures, we have used without adjustment two equations from the earlier work... 

T. B. Douglas, Conversion of Existing Calorimetrically Determined Thermodynamic Properties to the Basis of the International Practical Temperature Scale of 1968, J. Res. Natl. Bur. Stand. (U.S.) Sect. A 73, 451 (1969). (Formulas for converting H, Cp, S, and G from one temperature scale to another. Differences between the two scales are tabulated from 90 to 10 000 K.)... 

Convert between the Celsius and Kelvin temperature scales. 

Dimensional analysis is a method of problem-solving that focuses on the units used to describe matter. For example, if you want to convert a temperature in degrees Celsius to a temperature in kelvins, you focus on the relationship between the units in the two temperature scales. Scale drawings such as maps and the blueprint in Figure 2-8 are based on the relationship between different units of length. 

We know the volume of the sample at one temperature and wish to know its temperature corresponding to a second volume (constant pressure). We can solve Charles s Law for the second temperature. We must remember to carry out calculations with all temperatures expressed on the Kelvin scale, converting to or from Celsius as necessary. 

C can be regarded as the absolute zero of temperature. Since there cannot be less than zero volume, there can be no temperature colder than 273 °C. The temperature scale that has been devised using this fact is called the Kelvin, or absolute, temperature scale. A comparison of the Kelvin scale and the Celsius scale is shown in Figure 9-1. It is seen that any temperature in degrees Celsius may be converted to Kelvins by adding 273°. It is customary to use capital T to represent Kelvin temperatures and small t to represent Celsius temperatures. 

Kelvin absolute temperature scale and designated by °K. Temperatures in Fahrenheit (°F) can be converted to Kelvin by the following formula... 

Figure 1.10 summarizes the relationships between the three common temperature scales. In Chapter 8, we will use these relationships to convert measurements from one temperature scale to another. 

Using the freezing point of water to compare the three temperature scales (0°C, 273 K, and 32°F) and knowing how the size of the degree compares, it is possible to develop equations to convert a temperature on one scale to the corresponding temperature on another. 

Skill 3.1d-Convert between Kelvin and Celsius temperature scales... 

Since we are assuming, for the present, that only the ideal gas Kelvin temperature scale has a firm thermodynamic basis, we will use it. rather than the Fahrenheit and Celsius scales, in all thermodynamic calculations. (Another justification for the use of an absolute-temperature scale is that the interrelation between pressure, volume, and temperature for fluids is simplest when absolute temperature is used.) Consequently, if the data for a thermodynamic calculation are not given in terms of absolute temperature, it will generally be necessary to convert these data to absolute temperatures using Eqs. 1.4-4. ... 

Figure 10. Borehole temperature versus depth as measured in central Gieeidand, and as simulated by Culfey et al. (1995). The model was a coupled heat- and ice-flow computation driven by the record of the ice converted to temperature assuming a linear relation. The spatial dependence of on temperature is approximately 0.65 per mil per degree, which provides a poor fit to the data the optimal model differs from this by a factor of 2, and provides a much better fit. (A) The profile from the bed (height 0) to the surface (height 1, or -3050 m) (B) the upper portion the profiles on an expanded temperature scale. In Figure lOA, the optimal and measured curves are indistinguishable in lOB, the small differences between the optimal and measured curves indicate time-variation of the calibration of 5 0 to temperature.

This table gives temperature corrections from older scales to the current International Temperature Scale of 1990 (see the preceding table for details on lTS-90). The first part of the table may be used for converting Celsius temperatures in the range -180 to 4000 °C from IPTS-68 or IPTS-48 to ITS-90. Within the accuracy of the corrections, the temperature in the first column may be identified with either or The second part of the table is... 

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