Physics
(a) Write an expression for the heat energy liberated by a hot body.
(b) Some heat is provided to a body to raise its temperature by 25°C. What will be the corresponding rise in temperature of the body as shown on the Kelvin scale?
(c) What happens to the average kinetic energy of the molecules as ice melts at 0°C?
Calorimetry
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Answer
(a) The expression for the heat energy liberated by a hot body is:
ΔQ = mcΔT
where
m = mass of substance,
c = specific heat capacity of substance,
ΔT = change in temperature
(b) Rise in temperature will be the same on both Celsius and Kelvin scale as a degree (or temperature difference) is same on both the Celsius and Kelvin scales i.e.,
Δt °C = ΔT K
(c) When ice melts at 0°C, average kinetic energy of the molecules will remain the same. If heat is coming into a substance during a phase change, then this energy is used to break the bonds between the molecules of the substance.
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