A piece of copper of mass m₁ = 300 g with initial temperature t₁ = 97°C is placed into a calorimeter in which the water of mass m₂ = 100 g is at a temperature t₂ = 7°C. Find the entropy increment of the system by the moment the temperaturese equalize. The heat capacity of the calorimeter itself is negligibly small. ( S C u S_{Cu} S C u = 0.39 J/g-K)
Physics · Thermodynamics
JEE Advanced

Question

A piece of copper of mass m₁ = 300 g with initial temperature t₁ = 97°C is placed into a calorimeter in which the water of mass m₂ = 100 g is at a temperature t₂ = 7°C. Find the entropy increment of the system by the moment the temperaturese equalize. The heat capacity of the calorimeter itself is negligibly small. ( S C u S_{Cu} S C u = 0.39 J/g-K)

Physics · Thermodynamics

G1 Physics · Accepted Answer

Use the first law Q=ΔU+W (W by the gas), ΔU=nCᵥΔT for an ideal gas, and the appropriate process relation. For Carnot devices, let T₁ be the cold-reservoir temperature and T₂ be the hot-reservoir temperature; η=1-T₁/T₂ and COP=T₁/(T₂-T₁). Substituting the given values gives 4.4.