Question

Constants Periodic la Consider benzene in the gas phase, Co H.(g). Part A What is the standard enthalpy change for the reaction that represents breaking all the bonds in gaseous benzene, C6H6(g)? Benzene Express your answer to one decimal place and include the appropriate units. Use the heat of formation, AH values below to answer the questions. T! Å R ? AH Substance (kJ/mol) H(g) 217.94 C(g) 718.4 C.H8 (8) 82.9 O 2 Units AH = Value Submit Request Answer Part B What is the chemical equation for the reaction that corresponds to breaking just the carbon-carbon bonds in gaseous benzene, C.H. (g)? Indicate the phase of each species in your answer. Express your answer as a chemical equation including phases. LE ACC O 2 ? Submit Request Answer

Answer 1

Answer -

Part A -

Given,

Species	$\Delta$H$\degree$f (kJ/mol)
H (g)	217.94
C (g)	718.4
C6H6(g)	82.9

$\Delta$H^$\degree$_rxn = ?

The reaction of breaking of all bonds of Gaseous Benzene (C₆H₆)

If all C-H and C-C bonds are breaked no bonds left only except C (g) and H (g)

C6H6 (g) $\rightarrow$ 6 C (g)+ 6 H (g)

We know that,

$\Delta$H^$\degree$_rxn = $\sum$ n * $\Delta$ H^$\degree$_f (products) - $\sum$ n * $\Delta$ H^$\degree$_f (reactants)

where n = stiochiometric coefficient

$\Delta$H^$\degree$_rxn = 6 mol * $\Delta$ H^$\degree$_f (C (g)) + 6 mol* $\Delta$ H^$\degree$_f (H (g)) - 1 mol *$\Delta$H^$\degree$_f (C₆H₆ (g))

Put the values,

$\Delta$H^$\degree$_rxn = (6mol * 718.4 kJ/mol) + (6mol * 217.94 kJ/mol) - (1 mol *82.9 kJ/mol)

$\Delta$H^$\degree$_rxn = 5535.14 kJ [Answer]

PART b)

Given,

C₆H₆ (g)

reaction of breaking of Just C-C bond

If all the C-C bond are breaked then 6 C-H bonds are left. So, the reaction is

C₆H₆ (g) $\rightarrow$ 6 CH (g) [Answer]