Metal fusion enthalpies

The melting peak and fusion enthalpy of phase-change nanoparticles during thermal analysis provide information about the type and concentration of biomarkers, respectively. The different types of nanoparticles used are metal (indium, tin, aluminum, cadmium, copper, magnesium, silver, bismuth, gadolinium, and palladium), bimetal alloy (lead-tin, or any combination from the aforementioned metals) or eutectic alloys [86]. Use of nanoparticles helped increase the sensitivity to picomolar or femtomolar range. 

Self-Test 6.10A The enthalpy of fusion of sodium metal is 2.6 kj-mol 1 at 25°C, and the enthalpy of sublimation of solid sodium at that temperature is 101 kj-mol 1. What is the enthalpy of vaporization of sodium at 25°C ... 

Here A vac. S and A vacH are the molar entropy and enthalpy of formation of the defects. Using a pure metal like aluminium as an example, the fractional number of defects, heat capacity and enthalpy due to defect formation close to the fusion temperature are 5-10-4, 0.3 J K-1 mol-1 and 30 J mol-1 [30],... 

Solid chromium adopts a body-centered cnbic stracture and crystallizes in the space gronp Imim with a = 288.46pm its density is 7.19 gcm (at 293 K). The metal melts at 2130 ( 20) K and boils at 2945 K the corresponding enthalpies are A//fusion = 15.3kJmoP and A//vap = 348.78 kJ moU. Values of various thermodynamic functions are listed in Table 2. Some other values are thermal conductivity 93.7 W m (at300 K), electrical resistivity ... 

It takes 15 kWh (kilowatt hours) of electrical energy to produce 1.0 kg of aluminum metal from aluminum oxide by the Hall-Heroult process. Compare this value with the amount of energy necessary to melt 1.0 kg of aluminum metal. Why is it economically feasible to recycle aluminum cans (The enthalpy of fusion for aluminum metal is 10.7 kj/mol and 1 watt = 1 J/s.)... 

At the hypercooling limit, the whole melt grows below Tm [15], unlike the general case where the remaining melt grows isothermally at Tm- AThyp for, e.g., Ni, a closely packed metal, is 446 K, while it is 1,977K for Si because of the large enthalpy of fusion, AHf. Therefore, it is not realistic that the Si melt undercools beyond AThyp. 

Values for the enthalpies of fusion of alkali-metal cryolites may be obtained, using an aneroid, inverse-drop calorimeter with adiabatic shields.475... 

Mixtures of molten alkali metal halides and hydroxides have a potential use in energy storage, where the relatively high value of the enthalpy of fusion is used. Molten carbonates of alkali metal halides are used as electrolytes in molten carbonate fuel cells. A big industrial field, where oxide melts are predominantly used, is the glass industry. Here, the high affinity of these melts to under-cooling and glass formation is exploited. 

Similarly, Holm et al. (1973) measured the enthalpy increments Hr — 7/298 of the congmently melting compounds of 2 1 and 1 1 alkali metal chlorides and magnesium chloride using a high-precision adiabatic drop calorimeter. From the results obtained at several experimental temperatures corresponding with solid and liquid samples, they determined the enthalpies of fusion of these compounds. Values for heat capacities for the molten salt mixtures were also derived. The heat capacities for the 2 1 and 1 1 compounds were estimated from those of the binary compounds according to the relation... 

In this study, the thermal properties of a number of metals were determined in their liquid state using levitation calorimetry. Liquid zirconium was studied from 2233 to 3048 K, with a reference temperature of 2128 K (the melting point of zirconium). The change in the enthalpy increment over this temperature range was found to be linear indicating that the heat capacity was constant and equal to (40.7 0.7) J-K -mof. From the measurements, the heat of fusion was found to be (14.7 0.3) kJ-mof. These values are accepted by this review. 

The enthalpies of fusion of ten other metals and alloys (plus CaCp) were also determined, and were within 5% of the literature values for these materials, except for Bi and Mg, where the deviations were 6.0 and 8.6%. 

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