Kelvin scale

Kelvin scale See absolute temperature. kephaUn See cephalins. 

Cp, specific heat (at temperature specified on the Kelvin scale) for the physical state in existence (or specified c, Iq, g) at that temperature in J mol ... 

The absolute temperature scale that corresponds to the Celsius scale is the Kelvin scale for the Fahrenheit scale, the absolute scale is called the Rankine scale. The Celsius scale reads 0 when the Kelvin scale reads 273 the Fahrenheit scale reads 0 when the Rankine scale reads 460. These relationships are shown in Figure 1. 

Carnot s research also made a major contribution to the second law of thermodynamics. Since the maximum efficiency of a Carnot engine is given by 1 -T( H, if the engine is to be 100 percent efficient (i.e., Cma = 1), Tc must equal zero. This led William Thomson (Lord Kelvin) to propose in 1848 that Tf must be the absolute zero of the temperature scale later known as the absolute scale or Kelvin scale. ... 

The internal energy of all gases depends on the temperature of the gas. For an ideal gas, the internal energy depends only on the temperature. The temperature is most appropriately measured on the Kelvin scale. The contribution to the internal energy from the random kinetic energy of the molecules in the gas is called thermal energy. 

The temperature of a gas is ordinarily measured using a thermometer marked in degrees Celsius. However, as we will see in Section 5.2, in any calculation involving the physical behavior of gases, temperatures must be expressed on the Kelvin scale. To convert between °C and K, use the relation introduced in Chapter 1 ... 

The Rankine temperature scale resembles the Kelvin scale in that 0° is taken to be the lowest attainable temperature (0°R = 0 K). However, the Rankine degree is the same size as the Fahrenheit degree, whereas the Kelvin degree is the same size as die Celsius degree. What is die value of die gas constant in L-atm/(mol-°R) ... 

The boiling points and freezing points in degrees Centigrade of certain liquids are listed below. Express these temperatures on the absolute temperature (degree Kelvin) scale. 

Absolute temperature, 57 Kelvin scale, 58 Absolute zero, 58... 

The Kelvin scale of absolute temperatures is described in Appendix IB the temperature in kelvins (K) is obtained by adding 273.15 to the temperature in degrees Celsius (°C). 

A note on good practice Note that the volume (or the pressure) doubles when the temperature is doubled on the absolute (Kelvin) scale, not when it is doubled on the Celsius scale. An increase from 20°C to 40°C corresponds to an increase from 293 K to 313 K, an increase of only 7%. 

SOLUTION To find the pressure of the gas, we substitute the data into Eq. 26 after converting the temperature into the Kelvin scale. We use R in units that match those given (atmospheres and liters). 

To use this equation, identify the value of Aw for the reaction, convert the temperature to the Kelvin scale, and rearrange it to solve for Kr. 

The corresponding expression for conversion between the Celsius and Kelvin scales is... 

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. 

Scientists use two units for temperature, the Celsius (°C) scale and the Kelvin (K) scale. These scales are shown schematically in Figure 1-18. Unlike other scientific units, the unit size of the Celsius and Kelvin scales is the same, but their zero points differ. For both scales, the difference in temperature between the freezing and boiling points of water is defined to be 100 units. However, the temperature at which ice melts to liquid water is 0 °C and 273.15 K. 

To use the ideal gas equation for quantitative calculations, we must express each quantity in appropriate units. The ideal gas equation holds only when temperature is expressed using an absolute scale. We will always use the Kelvin scale, applying the conversion introduced in Chapter E 7 (K) = T(° C) + 273.15. Typical laboratory pressures are expressed in atmospheres, and typical laboratory volumes are expressed in liters. For this choice of... 

Write an equation for the combined gas law using temperature in Celsius. Explain why the Kelvin scale is more convenient. 

A (1) symbol for mass number. (2) symbol for ampere. absolute temperature temperature on the Kelvin scale. 

The XIII Conference Generale des Poids et Mesures adopts the Kelvin scale with a single fixed point 273.16K. The unit of temperature is designated Kelvin its symbol is K. 

SB For oxygen The increase in the volume will be directly proportional to the temperature increase (Kelvin scale). Assuming that the pressure remains constant,... 

Kelvin then replotted his data, this time extrapolating each graph till the volume of the gas was zero, which he found to occur at a temperature of -273.15 °C see Figure 1.5. He then devised a new temperature scale in which this, the coldest of temperatures, was the zero. He called it absolute zero, and each subsequent degree was equal to 1 °C. This new scale of temperature is now called the thermodynamic (or absolute) scale of temperature, and is also sometimes called the Kelvin scale. 

Note degrees in the Kelvin scale do not have the degree symbol. The units have a capital K, but the noun kelvin has a small letter. 

Many times, especially in working with gases, chemists use the Kelvin scale. Water freezes at 273-15 K and boils at 373-15 K. To convert from Celsius to kelvin ... 

Celsius degrees and Kelvin degrees are the same size. The Kelvin scale begins at absolute zero. This is the temperature at which the particles in a substance have no kinetic energy. Therefore, Kelvin temperatures are never negative. By contrast, 0°C is set at the melting point of water. Celsius temperatures can be positive or negative. 

The Celsius scale is a relative scale. It was designed so that water s boiling point is at lOO C and water s melting point is at 0 C. The Kelvin scale, on the other hand, is an absolute scale. It was designed so that 0 K is the temperature at which a substance possesses no kinetic energy. The relationship between the Kelvin and Celsius scales is shown in Figure 5.2, and by the following equation. 

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