How many grams of coffee must evaporate from 350g of coffee in a 100-g glass cup to cool the coffee and the cup from 95.0 °C to 45.0 °C ? Assume the coffee has the same thermal properties as water and that the average heatof vaporization is 2340 kJ/kg (560 kcal/g). Neglect heatlosses through processes other than evaporation, as well as the change in mass of the coffee as it cools. Do the lattertwo assumptions cause your answer to be higher or lower than the true answer?
Energy transfer
The flow of energy from one region to another region is referred to as energy transfer. Since energy is quantitative; it must be transferred to a body or a material to work or to heat the system.
Molar Specific Heat
Heat capacity is the amount of heat energy absorbed or released by a chemical substance per the change in temperature of that substance. The change in heat is also called enthalpy. The SI unit of heat capacity is Joules per Kelvin, which is (J K-1)
Thermal Properties of Matter
Thermal energy is described as one of the form of heat energy which flows from one body of higher temperature to the other with the lower temperature when these two bodies are placed in contact to each other. Heat is described as the form of energy which is transferred between the two systems or in between the systems and their surrounding by the virtue of difference in temperature. Calorimetry is that branch of science which helps in measuring the changes which are taking place in the heat energy of a given body.
How many grams of coffee must evaporate from 350g of coffee in a 100-g glass cup to cool the coffee and the cup from 95.0 °C to 45.0 °C ? Assume the coffee has the same thermal properties as water and that the average heat
of vaporization is 2340 kJ/kg (560 kcal/g). Neglect heat
losses through processes other than evaporation, as well as the change in mass of the coffee as it cools. Do the latter
two assumptions cause your answer to be higher or lower than the true answer?
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