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:
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
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...