From the data below, calculate the total heat (in J) needed to convert 0.333 mol of gaseous ethanol at 300°C and 1 atm to liquid ethanol at 25.0°C and 1 atm:

Solution 16P

Here we have to calculate the total heat (in J) needed to convert 0.333 mol of gaseous ethanol at 300°C and 1 atm to liquid ethanol at 25.0°C and 1 atm.

boiling point at 1 atm: 78.5oC = 40.5 kJ/mol

Cgas : 4.21 J/g oC C liquid = 2.45 J/goC

Step-1

Given:

Mol of ethanol = 0.333 mol

Molar mass of ethanol = 46.07 g/mol

Mass of ethanol = 0.33 mol46.07 g/mol = 15.34 g ethanol

Here the entire process has been carried out by three phases i.e cooling vapor to bp , then the phase of condensing vapor and the 3rd one is cooling of liquid. We have to calculate the heat required for all the three phases and the total heat required can be calculated by the addition of all the three processes.

(1) Cooling vapor to boiling point

The heat required can be calculated as,

q1 = Cm

Where C is the heat capacity (for ethanol = 1.43 J/goC)

m is the mass

is the change in temperature

q1 = 1.43 J/goC 15.34 g [78.5...