A 38.9 g block of copper whose temperature is 490 K is placed in an insulating b

Question

A 38.9 g block of copper whose temperature is 490 K is placed in an insulating box with a 68.6 g block of lead whose temperature is 157 K. (a) What is the equilibrium temperature of the two block system? (b) What is the change in the internal energy of the two-block system between the initial state and the equilibrium state? (c) What is the change in the entropy of the two-block system? The heat capacities of copper and lead are 386 /kg.K and 128 l/kg.K, respectively (a) Number (b) Number (c) Number Click if you would like to Show Work for this question: Open Show Work Units Units Units

Explanation / Answer

A) Tf = (mc Cc Tic + mpb Cpb Tipb)/ (mcCc + mpbCpb) = 367.12 K

B) Since the system is thermally insulated and no work is done, the change in internal energy is Zero.

C) delta S = mcCc ln(367.12/ 490) + mpb Cpb ln(367.12/ 157) = -4.34 + 7.46 = 3.12 J/K

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