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  Analysis    Sources of Error o   Unaccounted heat loss may be a source of error in the experiment. The equation used in computing the latent heat of fusion of ice assumes that the system is perfectly insulated and that there is no loss of heat to the surroundings. o   Instrument limitations may also be a factor. Temperature readings were obtained from an alcohol thermometer, which has limited marks corresponding to the temperature. The temperature is left to human estimation whenever the temperature is between two lines.   o   Another possible source of error may arise from human factors. Reproducibility of the data gathered in the experiment may be dependent if the temperature of the ice cube used is exactly zero, and not sub-zero degrees Celsius.    Concepts or Principles Used o   Calorimetry was the main concept observed throughout the experiment. The relationship  between the change in energy of a system brought upon by a change in temperature, and a change in phase was determined.   o   The concept of calorimetry is derived from the first law of thermodynamics. The First Law of Thermodynamics states that heat is a form of energy, and thermodynamic processes are therefore subject to the principle of conservation of energy.      Data-Concept Relationship   o   In the determination of the total energy in the system, it is found that other than the change in energy brought about by a change in temperature, energy is also absorbed by the system when there is a phase change present. o   It is found that energy brought about by a change in temperature, excluding phase change(s), is directly proportional to the change in temperature. That is, more energy is absorbed or given off by the system whenever there is a greater change in temperature. o   It is also found that there is a change in energy in a system whenever a phase change occurs. In the experiment, this was the latent heat of fusion. The energy associated in the phase change between solids and liquids, or vice versa. Conclusion One of the objectives of the experiment was to use the principle of calorimetry when combining objects of different temperatures. Another objective was to use the law of heat exchange in determining the  latent hear of fusion of ice. Both objectives were successfully obtained and thus an experimental value for the latent heat of fusion of ice was determined. The law of conservation of energy states that the total energy of an isolated system is constant; energy can be transformed from one form to another, but can be neither created nor destroyed. Mathematically, this can can be expressed as      +   = 0   Where, q is the energy in the form of heat. The equation above shows that energy is constant, it is neither created nor destroyed. Using this equation, energy changes brought about by a change in temperature and a change in phase may be computed. If the system is the ice and that the surroundings are the water and the calorimeter, the latent heat of fusion may be experimentally determined. Heat of fusion is the amount of heat energy required to change the state of matter of a substance from a solid to a liquid. When heat is supplied to a solid, it is found that the temperature climbs steadily until the melting point is reached and the first signs of liquid formation become evident. Thereafter, even though the surrounding is still supplying heat to the system, the temperature remains constant as long as both liquid and solid are present. After having done the experiment, I learned that there is also a release of energy whenever a substance goes through a phase change. With this, I have also learned a wider application of calorimetry. It can also be used to determine the amount of heat needed to physically change a substance’s phase.  This experiment made me think how the latent heat of fusion could be applied to engineering or to the fields of my study. As a Chemical Engineering and Chemistry student, I think that the principle of the latent heat can  be applied to the field Chemistry in Thermodynamics. The first law of thermodynamics can be mathematically expressed as  =  +  Where U is the internal energy of the system, q is heat energy, and w is the work. Latent heat would be under the variable q because it as a form of heat energy. Rearranging the equation to solve for w. It can be seen that a high q makes it possible for a system to do more work. This is the concept between all engines. Engines are devices that convert heat to work. The latent heat of vaporization of water is significantly higher that its fusion. This is why steam engines were utilized during the early days because it could produce a lot of work due to the energy released by the system whenever it vaporizes to steam. (1) (2)

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Oct 7, 2019
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