Specific heat of metals

A sample of substance X has a mass of 123 g. When the sample releases 795 J of heat, its temperature falls from 45.1°C to 17.6°C. What is the specific heat of substance X  

Why is it important that a calorimeter be made of an insulating material  

Read the entire laboratory activity. Form a hypothesis about which of the three metals will cause the largest change in water temperature for its mass. Explain your reasoning. Record your hypothesis on page 46. 

Always wear safety goggles, gloves, and a lab apron. 

Broken glassware may have sharp edges. Be careful when using scissors. Use caution and proper protection when handling hot objects. 

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This rule was stated in 1819 by Dulong and Petit, and it indicates that the specific heat of a metal multiplied by the atomic weight is a constant. This relationship provides a way to estimate the atomic weight of a metal if its specific heat is known. How well the rule holds is indicated by the specific heats of metals shown in Table 7.9. 

The theory fails to explain the molar specific heat of metals since the free electrons do not absorb heat as a gas obeying the classical kinetic gas laws. This problem was solved when Sommerfeld (1) applied quantum mechanics to the electron system. 

The experimentally measured specific heat of metal group III nitrides and the phonon determined specific heat for several chosen Debye temperatures are presented in FIGURE 1. 

Specific heats of metals and hydrides are easily determined and typically fall in the range of 0.1-0.2 cal/g°C. Thermal conductivity is a little more difficult to determine. The conductivity of the metal or hydride phase is not sufficient the effective conductivity of the bed must be determined. This depends on alloy, particle size, packing, void space, etc. Relatively little data of an engineering nature is now available and must be generated for container optimization. Techniques to improve thermal conductivity of hydride beds are needed. As pointed out earlier, good heat exchange is the most important factor in rapid cycling. 

Much has been written about the failure of classical theory in interpretating the specific heat of metals and the subsequent development of a quantum theory of the perfect solid state. It would be quite impossible to give an adequate account of this development here, and the... 

At one time it was thought that the molar mass of indium was near 76 g moU. By referring to the law of Dulong and Petit (see Problem 7), show how the measured specific heat of metallic indium, 0.233 J g, makes this value unlikely. 

The water weight means the actual weight of the copper vessel multiplied by the specific heat of copper. It must not be forgotten that the specific heat of metals varies with the temperature, and this fact should be taken into consideration. 

Product Analysis is a chemical report that a particular product form, such as tubing or pipe fitting, is made from a specific heat of metal. Product analyses ensure that substitutions have not been made during processing the metal. Product analyses are called out as supplemental requirements in ASTM specifications and cost extra, unlike the MTR or COC. 

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 is approximately 25 J/°C. This observation, now called Dulong and Petit s law, was used to estimate the specific heat of metals. Verify the law for the metals listed in Table 6.1. The law does not apply to one of the metals. Which one is it Why ... 

TIL] Tilden, W. A., The specific heats of metals and the relation of specific heat to atomic weight. Part II., Proc. R. Soc. London, 71, (1902), 220-221. Cited on page 172. 

JAEA E] Jaeger, F. M., Veenstra, W. A., The exact measurement of the specific heats of solid substances at high temperatures. XVI. The specific heats of metallic thorium and of thorium dioxide between 20° and 1400° C, Proc. - Acad. Sci. Amsterdam, 21, (1934), 327-332. Citedonpages 91,115,410. 

Explain what happens to the melting point and specific heat of metals as the size changes from the bulk to the nanoscale. 

Fig. 12. The Stern-Gerlach type experimental setup for the measurements of magnetic moments and specific heats of metal clusters.

The hypothesis of the electron gas breaks down, however, in its application to specific heats. It implies that the thermal energies of electrons are equal to those of atoms, by the equipartition principle. But the specific heats of metals can be almost entirely accounted for by the atomic motions alone. Dulong and Petit s law, and indeed the Einstein and Debye relations, ignore any contribution firom the electrons to the energy, and yet in their respective spheres give a good enough account of the facts. 

Handbooks (such as reference 52) list the mean specific heats of metallic and non-metallic materials. 

The thermal characteristics of NR-metal composites are close to the properties of metals, whereas the mechanical properties and the processing methods are typical of polymers.Thermally conducting, but electrically insulating, polymer-matrix composites are increasingly important for electronic packaging because the heat dissipation ability limits the reliability, performance and miniaturization of electronics.Thermal properties such as thermal conductivity, thermal dilfusivity and specific heat of metal (copper, zinc, Fe and bronze) powder-filled polymer composites are investigated experimentally in the range of filler content 0-24% by volume. ... 

The thermal expansion coefficient, the electric resistivity, and the specific heat of metallic nanosolids or alloys increase inversely with solid size whereas the temperature coefiicient of resistivity and the critical temperature for magnetic transition drop inversely with solid size [46]. The emerging freedom of size... 

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