Element specific heat capacity

The high-temperature contribution of vibrational modes to the molar heat capacity of a solid at constant volume is R for each mode of vibrational motion. Hence, for an atomic solid, the molar heat capacity at constant volume is approximately 3/. (a) The specific heat capacity of a certain atomic solid is 0.392 J-K 1 -g. The chloride of this element (XC12) is 52.7% chlorine by mass. Identify the element, (b) This element crystallizes in a face-centered cubic unit cell and its atomic radius is 128 pm. What is the density of this atomic solid ... 

If a substance is heated without a change of state, the amount of heat required to change the temperature of 1 gram by 1° C is called the specific heat capacity of the substance. Similarly, the molar heat capacity is the amount of heat needed to raise the temperature of 1 mole of a substance by 1° C. Table 7-2 shows the heat capacities of several elements and compounds. 

In example 1, a volume throughput of 300 1/h is pumped at a rotational speed of 300 rpm. Eqs. 7.2 to 7.10 and the typical physical properties of density p=1000 kg/m3 and specific heat capacity c=2000 J/kg-K are used to calculate the back-pressure length, pumping efficiency, energy input and temperature rise in the polymer for the two available screw elements. 

Despite a wide range of specific heat capacities, the diatomic gases have molar heat capacities of about 29 J/moF°C, and the molar heat capacities of all the metallic elements are close to 26 J/moF°C. The latter generalization is known as the law of Dulong and Petit. 

The specific heat capacities of the metals nickel, zinc, rhodium, tungsten, gold, and uranium at 25°C are 0.444, 0.388, 0.243, 0.132, 0.129, and 0.116 J K g respectively. Calculate the molar heat capacities of these six metals. Note how closely the molar heat capacities for these metals, which were selected at random, cluster about a value of 25 J K mol b The rule of Dulong and Petit states that the molar heat capacities of the metallic elements are approximately 25 J K moUb... 

When an element or a componnd is heated, the energy reqnired to reach a certain temperature will depend on the amount of the snbstance present (for example, it takes twice as much energy to raise the temperature of 2 g of water by 1°C as it takes to raise the temperature of 1 g of water by 1°C). Thus, in defining the heat capacity of a snbstance, the amount of substance must be specified. If the heat capacity is given per gram of substance, it is called the specific heat capacity with units of J or J °C g . If the heat ca-... 

The first of these, due to Dulong and Petit, expresses a term called the atomic heat which is defined as the product of the relative atomic mass and the specific heat capacity. For all solid elemental substances, the atomic heat is assumed to be roughly constant ... 

Dulong and Petite law For a solid element the product of the relative atomic mass and the specific heat capacity is a constant equal to about 25 J mol K . Formulated in these terms in 1819 by the French scientists Pierre Dulong (1785-1838) and Alexis Petit (1791-1820), the law in modern terms states the molar heat capacity of a solid element is approximately equd to 31i where R is the gas constant. The law is only approximate but applies with fair accuracy at normal temperatures to elements with a simple crystal structure. gj fElUlillJlIIIIH. ... 

Most polymer products approximate to series of flat or curved plate-like elements joined together. This simplifies the analysis of heat flow by reducing it to a one-dimensional problem—see Figure 7.16. The wall of the component is of half-thickness L and is cooled by an environment ai temperature T. Within a polymer of thermal conductivity k, density p, and specific heat capacity c, the variation of temperature T is then governed by the equation of one-dimensional heat conduction ... 

In the nineteenth century two scientists named Dulong and Petit noticed that for a solid element, the product of its molar mass and its specific heat capacity is approximately 25 J °C . This observation, now called Dulong and Petit s law, was used to estimate the specific heat capacity of metals. Verify the law for the metals listed in Table 7.1. The law does not apply to one of the metals. Which one is it Why ... 

Dulong and Petit s law The law that states that the molar heat capacity of a solid element is approximately equal to 3R, where R is the GAS CONSTANT (25 J K" mol" ). The law applies only to elements with simple crystal structures at normal temperatures. At lower temperatures the molar heat capacity falls with decreasing temperature. Molar heat capacity was formerly called atomic heat - the product of the relative atomic mass of a substance and its specific heat capacity. 

T = Temperature, Cp = specific heat capacity, S = Entropy, H = Enthalpy, G = free Enthalpy, p = partial pressure of the pure elements... 

Dulong and PetHIS law The product of a solid element s relative atomic mass and its specific heat capacity is approximately 6.4. This can be used to find a solid s valency if its equivalent mass has been determined. 

The heat transfer from the solid catalyst to the fluid is assumed to follow Newton s law of cooling the area over which this heat transfer takes place is assumed to be a known constant As-The fluid density p and specific heat capacity Cp are constant the solid catalyst particles are all assumed to be identical, with identical density p and identical specific heat capacity Cps-The catalyst packing is assumed to be uniform, so that across any cross section of the reactor, the number and arrangement of particles are identical. (This allows the use of arbitrarily located microscopic element for developing the model). 

Table 6.2 Specific Heat Capacities (c) of Some Elements, Compounds, and Materials ...

In order to use the methods presented above to classify the chemical elements, the problem we are first faced with is to decide the characteristics this classification is built upon. We started with 10 physical properties relative atomic mass, A (1), density, p (2), melting point, Tf (3), boiling point, T, (4), Pauling electronegativity, x (5), enthalpy of vaporization, AH (6) and fusion, AHf (7), specific heat capacity, Cs (8), first ionization energy, E (9), and covalent radius, r (10). 

The results of model version J are also depicted (as broken lines) in Fig. 4.25. This model version is similarly simple and almost identical to model version C, apart from the fact the heat transfer coefficient from the heating element is now calculated by assuming an infinitely large specific heat capacity of the particles in Martin s model. This is equivalent to saying that the evaporative sink in the... 

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