The heat of fusion of acetone (CH 3 COCH 3 ) at its normal melting point of -95
ID: 103580 • Letter: T
Question
The heat of fusion of acetone (CH3COCH3) at its normal melting point of -95°C is 5.7 kJ/mol, while its heat of vaporization at its normal boiling point of 56°C is 30.1 kJ/mol.
(a) Use these data to calculate the heat of sublimation for CH3COCH3. ______kJ/mol
Is your answer precise or is it approximate? _________
(b) At 298 K, the standard heat of formation of CH3COCH3(l) is -248.4 kJ/mol while the standard heat of formation of CH3COCH3(g) is -217.1 kJ/mol. Use this to calculate the heat of vaporization of acetone.______kJ/mol.
Is your result for part (b) larger or smaller than the value given in the statement of the problem? _________
Explanation / Answer
a)
approx sublimation:
Hsub = Hfusion + Hvapor = 5.7+30.1 = 35.8 kJ/mol
this is approximate, since we assume T° change is neglegible between 56 and -95°C
b
Hsub = CH3COCH3(g) - CH3COCH3(l) = -214.1--248.4 = 34.3 kJ/mol
this is smaller, due to the change in temperature most likely
Related Questions
Navigate
Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.