You need to fi nd the enthalpy of sublimation of solid A at 300 K. The following equilibrium vapor pressure measurements have been made on pure A: (1) at 250 K, the pressure is 0.258 bar and (2) at 350 K, the pressure is 2.00 bar. The following heat capacity data are known:

(a) Calculate the enthalpy of sublimation, assuming Δhsub is constant.

(b) Calculate the enthalpy of sublimation, accounting for the temperature variation of Dhsub.

(c) Estimate the error in the constant T assumption.

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J - 40 [MK] mol C J [K] mol K and c = 40+ 0.1T