(a) Using the thermochemical tables provided, calculate the standard molar enthalpy of combustion at 298 K for the following hydrocarbon: C C2H4 (g ) (ethene)
(b) If a combustion reaction were carried out in a bomb calorimeter using 55g of your compound, what would be the amount of heat released?
(c) Estimate the standard molar enthalpy of combustion of the compound used in part (a), at a temperature of 376.9K, given the following molar heat capacities:
|
|
Cp,m/ J K-1 mol-1
|
|
A C3H8 (g)
|
73.5
|
|
B C4H10 (g )
|
97.5
|
|
C C2H4 (g )
|
43.6
|
|
D C3H6 (g )
|
63.9
|
|
EC4H8 (g )
|
85.7
|
|
O2 (g)
|
29.4
|
|
CO2 (g)
|
37.1
|
|
H2O (l)
|
75.3
|
What assumption has been made in your calculation?
(d) From the mean bond enthalpy data given below, estimate the enthalpy change for the complete combustion of one mole of your compound at 298 K. (The molar enthalpy of vaporization of water is 45.0 kJ mol-1 at 298K).
|
Bond
|
C-H
|
O=O
|
O-H
|
C=O
|
C-C
|
C=C
|
|
Mean bond enthalpy/kJmol-1
|
414
|
499
|
460
|
799
|
347
|
612
|
(e) Comment on your answers to parts (a) and (d).