In thermodynamics there is a rule that describes the ratio of vaporization of li
ID: 518841 • Letter: I
Question
In thermodynamics there is a rule that describes the ratio of vaporization of liquid to boiling point (in K). You will be asked to utilize the equation below to fulfill the requirements of the assignment. AH 88 mol K 1. Calculate and complete the data table below, using the equation above and your text book. Boiling Point Tb Experimentally Calculated AHvap Calculated ASvap Substance (Celsius) Determined AHvap J/mol) (kJ/mol K) Ethanol 38600 29100 Acetone 30700 Benzene 29200 Chloroform 22700 Formic Acid 28900 Hexane Water 40660Explanation / Answer
1) and 4) together
For ethanol, Tb = 78.37 °C = 351.52 K
Hvap = 88 J/mol K * 351.52 K = 30933.76 J/mol
Svap = Hvap,exp / Tb = 38.6 kJ/mol / 351.52 K = 0.1098 kJ/mol K
Gvap = Hvap - TSvap
Gvap = 30.933 kJ/mol - 351.52 K*0.1098 kJ/mol K = -7.667 kJ/mol
Since Gvap is negative , it is spontaneous.
For acetone,
Tb = 56 + 273.15 = 329.15 K
Hvap = 329.15 K * 88 J/mol K = 28.9652 kJ/mol
Svap = 29.1 kJ/mol / 329.15 K = 0.0884 kJ/mol K
Gvap = 28.9652 - 329.15 K*0.0884 kJ/mol K = -0.13166 kJ/mol
It is spontaneous.
For benzene,
Tb = 80.1+273.15 = 353.25K
Hvap = 353.25K* 88 J/molK = 31.086 kJ/mol
Svap = 30.7 kJ/mol / 353.25K = 0.08690 kJ/mol K
Gvap = 31.086 - 353.25*0.08690 = + 0.388575 kJ/mol
It is not spontaneous.
For chloroform,
Tb = 61.2 + 273.15 = 334.35 K
Hvap = 334.35 K * 88 J/mol K = 29.4228 kJ/mol
Svap = 29.2 kJ/mol / 334.35 K = 0.08733 kJ/mol K
Gvap = 29.4228 - 334.35*0.08733 = 0.22401 kJ/mol
It is not spontaneous.
For Formic acid,
Tb = 100.8 + 273.15 = 373.95 K
Hvap = 373.95 K *88 J/mol K = 32.9076 kJ/mol
Svap = 22.7 kJ/mol / 373.95 K = 0.06070 kJ/mol K
Gvap = 32.9076 - 373.95* 0.06070 = 10.2088 kJ/mol
It is not spontaneous.
For Hexane,
Tb = 68 + 273.15 = 341.15 K
Hvap = 341.15 K * 88 J/mol K = 30.0212 kJ/mol
Svap = 28.9 kJ/mol / 341.15 K = 0.08471 kJ/mol K
Gvap = 30.0212 - 341.15 K*0.08471 = 1.1223 kJ/mol
It is not spontaneous.
For water,
Tb = 373.15 K
Hvap = 373.15 K * 88 J/mol K = 32.8372 kJ/mol K
Svap = 40.66 kJ/mol / 373.15 K = 0.10896 kJ/mol K
Gvap = 32.8372 - 373.15*0.10896 = -7.8212 kJ/mol
It is spontaneous.
2) ( [ |exp value - calc value| ] / calc value ) * 100 = calculate this value
if it exceeds 10% then identify and include them.