The sublimation of zinc (mass per mole 5 0.0654 kg/mol)

Chapter , Problem 102

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The sublimation of zinc (mass per mole 5 0.0654 kg/mol) takes place at a temperature of 6.00 3 102 K, and the latent heat of sublimation is 1.99 3 106 J/kg. The pressure remains constant during the sublimation. Assume that the zinc vapor can be treated as a monatomic ideal gas and that the volume of solid zinc is negligible compared to the corresponding vapor. Concepts: (i) What is sublimation, and what is the latent heat of sublimation? (ii) When a solid phase changes to a gas phase, does the volume of the material increase or decrease, and by how much? (iii) As the material changes from a solid to a gas, does it do work on the environment, or does the environment do work on it? How much work is involved? (iv) In this problem we begin with heat Q and realize that it is used for two purposes: First, it makes the solid change into a gas, which entails a change DU in the internal energy of the material, DU 5 Ugas 2 Usolid. Second, it allows the expanding material to do work W on the environment. According to the conservation-of-energy principle, how is Q related to DU and W? (v) According to the fi rst law of thermodynamics, how is Q related to DU and W? Calculations: What is the change in the internal energy of zinc when 1.50 kg of zinc sublimates?