1. For benzaldehyde, AvapH = 43.44 kJ/mol at 452.7 K (this is the standard boiling point). The heat capacity (in J/mol-K) of benzaldehyde vapor can be modeled for 400 < T< 600 K by 5.5456 x 106 Cp vapor (T) = 115.476 +0.164216 T T² (a) If AvapH = 43.8 kJ/mol at 424 K, and Cplia, the heat capacity of liquid benzaldehyde, is constant between 424 and 452.7 K, what is its value in J/mol.K? (b) Use the information from part (a) to find AvapH (in kJ/mol) at 400 K and 500 K.

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Whenever a substance is heated, its enthalpy increases, as suggested by the relation, ∆?=Cp∆?. However, the molar heat capacity itself is a function of temperature, and for N2 this function can be modeled as                             ?p(?)=? + ?? + c / T2  where a= 28.58 J/mol·K, b= 0.00377 J/mol·K2, and c= –5.0 x 104J·K/mol. (a) What does this formula for heat capacity predict for the value of ?p(?)at 300K? (b) Now, compute the enthalpy change associated with heating 0.62 moles of N2 from 300 to 600 K using the formula for ?p (?), and report the answer in J. (c) What is the difference between this value and one computed using the constant value for Cp at 300 K from part (a)? Report the absolute value of the difference in J.

Consider the situation where a binary liquid mixture (assume ideal solution) is slowly cooled at constant pressure until it begins to solidify. At the phase equilibrium between the solution and crystal, the chemical potentials of the solvent in each phase must be equal: u** (T,P)= µ"(T,P)+ k;Tlnx ... Equation (1) X, L denotes the crystal and liquid phase, respectively. Since Au = µ*L **: | Aµ = -kgTlnx ... Equation (2) Can you apply Equation (2) at non-phase change temperatures? Why?