Maximum Heat Transfer by Liquids at Different Temperatures
Maximum Heat Transfer by Liquids at Different Temperatures
Set the initial temperature and mass of a sample of liquid to calculate the maximum quantity of heat it can transfer when its temperature changes by The process is described by the equation , where is heat transferred (J), is mass (g), is specific heat of the substance (J/g °C), and is temperature (°C). Each liquid has a characteristic specific heat.
ΔT.
q=mcΔT
q
m
c
T
In the study [1] that inspired this work, a quantity of liquid was added to a massive amount of liquid nitrogen, so the final temperature winds up at 77 K ( degrees °C), whatever the mass and original temperature of the liquid. The purpose of this Demonstration is thus to clarify the conceptual difference between temperature and heat.
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Temperature is a measure of the average kinetic energy of the molecules in a body. Thus, temperature is an intensive property, independent of mass, while heat is an extensive property, proportional to the mass. A system does not "contain" any definite quantity of heat, but can only transfer heat along a temperature gradient.