PChem Please show work. answer if given, the steps are needed. 1) The change of

Question

PChem Please show work. answer if given, the steps are needed.

1) The change of internal energy cU° in the combustion of C60 (s) is -25,968 kJ/mol @ 25°C.

To do these problems each requires a balanced chemical equation. It is assumed that you can figure out the equation from the specific description of enthalpy.

a) What is the enthalpy of combustion, cH° of C60 (s)? ans. -25,968 kJ/mol

b) What is the enthalpy of formation, fH° of C60 (s)? ans. 2357 kJ/mol

c) What is the enthalpy of vaporization of C60 (s) to C (g) per mole of C (g)? ans. 677.4 kJ/mol

d) How does this compare with the enthalpy of vaporization of graphite and diamond to C (g)?

C(graphite) vaporization = 716. 7 kJ/mol. C(diamond) vaporization = 714. 8 kJ/mol.

For data to compare, look up fH° of carbon (diamond) and carbon (graphite) from the Table in the data section of our book.

Thank you

Explanation / Answer

a) enthalpy of combustion, cH° of C60 (s) = ?

C60 (s) + 60O2(g) ==> 60CO2(g)

q = C dT as dTn = 0 i.e 60-60 = 0 so dH = dE (dH = dE + PdV)

= -25968 constant = -25,968 kJ/mol

b) Enthalpy of formation of buckminsterfullerene

   60CO2(g) ==>   C60 (s) + 60 O2(g) dH = + 25986 KJ/mol

60[C(s) + O2(g) ==> CO2(g) dH = 60 x ( -393.510 KJ/mol)

60C(s) ==> C60(s) dH = dHf[C60] = 25592.49 KJ

c) Enthalpy of vaporization =

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