ThermochemistryHard
Question
Which of the following statement(s) is/are ture?
Options
A.ᐃE = 0 for combustion of C2H6(g) in a sealed rigid adiabatic container
B.ᐃfHo (S, monoclinic) ≠ 0
C.If dissociation energy of CH4 (g) is 1656 kJ/mol and C2H6(g) is 2812 kJ/mol, then value of C − C bond energy will be 328 kJ/mol
D.If ᐃHf(H2O,g) = - 242 kJ/mol; ᐃHvap (H2O, l) = 44 kJ/mol then ᐃfHo (OH- ,aq.) will be - 142 kJ/mol
Solution
(A) ᐃE will be - ve for combustion reactions
(B) ᐃHfo (S, rhombic) = 0
(C) CH4(g) → C(g) + 4H (g) ᐃH = 1656 kJ/mole = 4 ∈C-H
C2H6(g) → 2C(g) + 6H (g) ᐃH = 2812 kJ/mole = 6 ∈C-H + ∈C-C
So ∈C-C = (2812 -
× 1656) kJ/mole = 328 kJ/mole
(D) Can not be concluded from given data.
(B) ᐃHfo (S, rhombic) = 0
(C) CH4(g) → C(g) + 4H (g) ᐃH = 1656 kJ/mole = 4 ∈C-H
C2H6(g) → 2C(g) + 6H (g) ᐃH = 2812 kJ/mole = 6 ∈C-H + ∈C-C
So ∈C-C = (2812 -
× 1656) kJ/mole = 328 kJ/mole(D) Can not be concluded from given data.
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