Two hundred kilograms per hour of an aqueous solution containing 20.0 mole% sodium acetate (NaC2H3O2) enters an evaporative crystallizer at 60°C. When the solution is exposed to the low pressure in the evaporator, 16.9% of the water evaporates, concentrating the remaining solution and causing crystals of sodium acetate trihydrate (NaC₂H₃O₂ ∙ 3H₂O) to form. The product is an equilibrium mixture of crystals and a saturated aqueous solution containing 15.4 mole% NaC₂H₃O₂.

The effluents (crystals, solution, and water vapor) are all at 50°C.

(a) Calculate the feed rate to the crystallizer in kmol/h.

(b) Calculate the production rate (kg/h) of trihydrate crystals and the mass flow rate (kg/h) of the liquid solution in which the crystals are suspended.

(c) Estimate the rate (kJ/h) at which heat must be transferred to or from the crystallizer (state which), using the following physical property data:

Heat of solution of anhydrous sodium acetate:

Heat of hydration:

(d) In a commercial process to produce crystalline sodium acetate trihydrate, what are several processing steps the slurry leaving the crystallizer might undergo?

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(Cp)all solutions = 3.5 kJ/(kg. °C) (Cp)crystals = 1.2 kJ/(kg.°C) (CpH,0(v) = 32.4 kJ/(kmol- °C) %3D (AĤ,)H»o = 4.39 x 104 kJ/kmol H2O