Heat capacity of silver

P10.9 We have seen that the heat capacity of silver at low temperatures can be represented by the expression... 

The heat capacity of silver was taken from C. Kittel. Solid State Physics, Wiley, New York, 1956. The heat capacities of diamond were taken from J. E. Desnoyers. and J. A. Morrison. The Heat Capacity of Diamond between 12.8 and 222 °K . Phil. Mag.. 3, 42-48 (1958) and A. C. Victor, Heat Capacity of Diamond at High Temperatures . J. Chem. Phvs.. 36. 1903-1911(1962). 

I7e. Heat Capacities at High Temperatures.—Although the theoretical treatment of heat capacities requires the limiting high temperature value to be 3/2, i.e., 5.96 cal. deg. g. atom , experimental determinations have shown that with increasing temperature Cv increases still further. The increase is, however, gradual for example, tfie heat capacity of silver is 5.85 cal. deg. g. atom at 300° K and about 6.5 cal. deg. g. atom at 1300° K. This increase is attributed mainly to the relatively free electrons of the metal behaving as an electron gas. By the use of the special form of quantum statistics, viz., Fermi-Dirac statistics, applicable to electrons, the relationship... 

The specific heat capacity of silver is 0.24 J/g °C. Express this in terms of calories per gram per Celsius degree. 

Systems may be in chemical or mechanical equilibrium, and they may also exhibit thermal equilibrium. If a hot object is placed in contact with a colder mass of the same material inside an insulated container, heat flows from the hot object into the colder object until the temperatures of the two are equal. Heat lost by the warm object is equal to the amount gained by the cold object. The amount of heat needed to raise the temperature of an object a certain amount is equal to the amount which that object would lose in cooling by the same amount. The amount of heat needed to warm or the amount lost when cooling equals the product of the specific heat (or heat capacity) of the substance, the mass, and the change in temperature. For example, if a 50-gram (1.8-ounce) piece of silver at 70°C (158°F) is placed in 50 grams (1.8 ounces) of water at 15°C (59°F), the principle of thermal equilibrium can be used to calculate the final temperature of the water and silver ... 

Use the empirical rule of Dulong and Petit stated in Problem 7 to estimate the specific heat capacities of vanadium, gallium, and silver. 

Q.9.10 After reaching 327.5°C, a large section of the metal chunk melts, demonstrating tliat the metal chunk is a mixture of at least two different metals. A 0.8 kg dull silver chunk has a specific heat capacity of 0.13 kJ/kg-K. Can the specific heat capacity of the remaining chunk be determined without directly measuring it If yes, calculate it. 

Example 1-1 Ethylene oxide is produced by direct oxidation with air using a bed of catalyst particles (silver on a suitable carrier). Suppose that the stream enters the flow reactor at 200°C and contains 5 mole % ethylene and 95% air. If the exit temperature does not exceed 260°C, it is possible to convert 50% of the ethylene to the oxide, although 40% is also completely burned to carbon dioxide. How much heat must be removed from the reaction, per mole of ethylene fed, in order not to exceed the limiting temperature The average molal heat capacity of. ethylene may be taken as 18 Btu/(lb mole) (°R) between 25 and 200°C and as 19 Btu/(lb mole)(°R) between 25 and 260°C. Similar values for ethylene oxide are 20 and 21 Btu/(lb mole)(°R). The pressure is essentially atmospheric. 

The third form (Fig. 7) differs only in detail from the second it was preferred for the experiments with liquid hydrogen, because it could be made of much smaller dimensions. The platinum wire was wound on the outside of the cylindrical silver vessel and covered, to avoid thermal losses, with silver foil which was soldered at the edges to give a better thermal contact this form has the advantage that the platinum wire docs not have to be introduced vacuum-tight into the inside of the silver vessel. In a small size and at low temperatures this form of calorimeter proved to be excellent. The heat capacity of the silver vessel could be calculated with good accuracy, but it was also directly determined by a series of... 

Table 10.1 shows that silver has a specific heat capacity of 0.24 J/g °C. The metal is silver. 

A piece of silver of mass 362 g has a heat capacity of 85.7 J/°C. What is the specific heat of sUvct ... 

Adiabatically operated single scanning calorimeters were used for determinations of the specific heat capacities of copper and brass (Sykes, 1935) and of silver, nickel, brass, quartz, and quartz glass (Moser, 1936). Sykes calorimeter is shown schematically in Figure 7.35. 

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