Sixty-five liters of liquid ethanol at 70.0C and 55 L of liquid water at 20.0C are to

Question:

Sixty-five liters of liquid ethanol at 70.0°C and 55 L of liquid water at 20.0°C are to be mixed in a wellinsulated flask. The energy balance for this constant pressure process is Q = ΔH.

(a) Neglecting evaporation and the heat of mixing, estimate the final mixture temperature. (As part of the calculation, use data in Table B.2 to estimate a linear formula for the heat capacity of liquid ethanol.)

(b) If the experiment were actually performed and the final mixture temperature were measured, it would almost certainly not equal the value estimated in Part (a). List as many reasons as you can to explain the observation. (There are at least seven of them, most involving approximations made in the estimation.)

able B.2

TABLE B.2 Heat Capacities Form 1: C,[kJ/(mol-C)] or [kJ/(mol-K)] = a + bT + cr + dT Form 2: C,k/(molC)j or [kJ/(mol-K)j = a + bT + cT2 Example: (C,)acetone(e) = 0.07196 + (20.10 x 10-5)r - (12.78 x 10-8)7? + (34.76 x 10-12)Tr*, where T is in °C. %3D