Thermodynamic Properties of Solid Solutions in the System Ag2S – Ag2Se 1. Introduction This paper is about the calculation of standard thermodynamic properties of the four solid solutions in the phase diagram of Ag2S – Ag2Se. They calculated these properties using the model of regular and subregular solutions. The four solid solutions are: a restricted fcc solid solution (γ- Ag2S-Ag2S1-xSe (x<0.3)), a complete bcc solid solution (β- Ag2S – Ag2Se), monoclinic solid solution (α) from Ag2S to Ag2S0.4Se0.6, and a orthorhombic solid solution (α) from Ag2S0.3Se0.7 to Ag2Se. There is also a miscibility gap between Ag2S0.4Se0.6 and Ag2S0.3Se0.7. In this region Gmix and Smix have been calculated using subregular model for asymmetric solutions. 2. Experimental information: The experimental methods used by them for the study of solid Fig.1. Phase diagram of Ag2S – Ag2Se solutions of Ag2S – Ag2Se are diffraction techniques, density measurements methods, and the temperatures of phase transitions. Fig. 1 is a typical phase diagram of Ag2S – Ag2Se system based on experimental data from many journals. According to this phase diagram the transition temperature for Ag2S is 176°C, and for Ag2Se it is 128°C. The melting temperature for Ag2S is 837°C and for Ag2Se it is 897°C. Pingitore et al. and Ponce studied this system using optical microscopy, electron- probe microanalysis and X – ray diffraction and they found that there are two solid solutions at ambient conditions. One series is monoclinic which is from Ag2S to Ag2S0.4Se0.6 and the other series is orthorhombic which is from Ag2S0.3Se0.7 to Ag2Se. 3. Model Description: The models used for the evaluation of standard thermodynamic properties of Ag2S – Ag2Se system are regular and subregular for solid solutions. At the high temperature the system is described by phase diagrams with a common minimum point on solidus and liquidus curves. In this region the standard thermodynamic properties are evaluated by using subregular solution model. While at low temperature region where there are two continuous solid solutions (monoclinic and orthorhombic) with a miscibility gap, the standard thermodynamic properties are evaluated by using both models of regular and subregular solutions.
The purpose for this lab was to use aluminum from a soda can to form a chemical compound known as hydrated potassium aluminum sulfate. In the lab aluminum waste were dissolved in KOH or potassium sulfide to form a complex alum. The solution was then filtered through gravity filtration to remove any solid material. 25 mLs of sulfuric acid was then added while gently boiling the solution resulting in crystals forming after cooling in an ice bath. The product was then collected and filter through vacuum filtration. Lastly, crystals were collected and weighed on a scale.
The complete experimental procedure is available in the General Chemistry Laboratory Manual for CSU Bakersfield, CHEM 213, pages 20-22, 24-25. Experimental data are recorded on the attached data pages.
Physical Chemistry Laboratory Manual, Physical Chemistry Laboratory, Department of Chemistry, University of Kentucky, Spring 2006.
The mean for the temperatures is 0.116 and the solvents is 20. We predicted the 37 Celsius would be the most absorbed, but it was the -20 Celsius which can be seen in the graph above.
Matter exists in three basic states: solid, liquid, or gas. A substance experiences a phase change when the physical characteristics of that substance change from one state to another state. Perhaps the most recognizable examples of phase changes are those changes from a solid to a liquid or a liquid to a gas. When a substance goes through a phase change, there is a change in the internal energy of the substance but not the temperature of the substance (Serway, et al. 611).
[9] 2009, “CRC Handbook of Chemistry and Physics, 90th edition,” American Chemical Society CNC Press, Boca Raton, pp. 631-637
From figure 4 and formula, essentially explain the lack of thermal expansion activity during β phase is due to the fact that tilt angle δ has settled at zero which causes the removal of expansion components and discontinuity
The purpose of performing this lab was to find the specific heat capacity of an unknown metal.
The objective of this experiment was to identify a metal based on its specific heat using calorimetry. The unknown metals specific heat was measured in two different settings, room temperature water and cold water. Using two different temperatures of water would prove that the specific heat remained constant. The heated metal was placed into the two different water temperatures during two separate trials, and then the measurements were recorded. Through the measurements taken and plugged into the equation, two specific heats were found. Taking the two specific heats and averaging them, it was then that
Mixed melting point was used to confirm the identity of the product. The smaller the range, the more pure the substance. When the two substances are mixed; the melting point should be the same melting range as the as the melting range obtained after filtering. If the mixed melting point is lower one taken from the crystals, then the two substances are different.
... model for the thermodynamics and fluid mechanics calculations for this system need to be presented.
To investigate the temperature change in a displacement reaction between Copper Sulphate Solution and Zinc Powder
Since the days of Aristotle, all substances have been classified into one of three physical states. A substance having a fixed volume and shape is a solid. A substance, which has a fixed volume but not a fixed shape, is a liquid; liquids assume the shape of their container but do not necessarily fill it. A substance having neither a fixed shape nor a fixed volume is a gas; gases assume both the shape and the volume of their container. The structures of gases, and their behavior, are simpler than the structures and behavior of the two condensed phases, the solids and the liquids
The Web. The Web. 28 Apr. 2014. The 'Standard' of the 'Standard'. Metal Melting 101 - How To.
In summary, the rate of cooling from the austenite phase is the main determinant of final structure and properties.