Adecorative "ice" sculpture is carved from dry ice (solid co2) and held at its sublimation point of –78.5°c. consider the process in which a co2 sculpture, weighing 389 g, sublimes on a granite tabletop. the temperature of the granite is 12.0°c and the process occurs reversibly. assume a final temperature for the co2 vapor of –78.5°c. the enthalpy of sublimation of co2 is 26.1 kj/mol. calculate the entropy of sublimation for carbon dioxide (the system) j/kmol

the answer is 303.15 or 303

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answer: semi-infinite solid initially at a uniform temperature of 400 ◦c is cooled at its surface by convection. the cooling fluid at a constant temperature of 200 ◦c has a convective coefficient (ha) of 250 w/m2.k. the physical properties of the solid: k = 20 w/m.k and α = 4 * 10-5  m2/s. using δx = 0.04 m and δt = 10 s. write the finite difference equations describing the transient heat transfer of the first five δx and the temperature profile after 30 s.