When enthyne is passed through a red hot tube, then formation of benzene takes place:
`Delta_(f)H_((C_(2)H_(2))(g))^(Theta) = 230 kJ mol^(-1)`
`Delta_(f)H_((C_(6)H_(6))(g))^(Theta) = 85kJ mol^(-1)`
Calculate the standard heat of trimerisation of ethyne to benzene:
`3C_(2)H_(2)(g) rarr C_(6)H_(6)(g)`

When ethyne is passed through a red hot tube, then formation of benzene takes place: H_(f(C_(2)H_(2))(g))^(@)=230kJ" "mol^(-1) DeltaH_(f(C_(6)H_(6))(g))^(@)=85kJ" "mol^(-1) calculate the standard heat of trimerisation of ethyne to benzene. 3C_(2)H_(2)(g)toC_(6)H_(6)(g)

If Delta_(f)H^(@) _(C_(3)H_(8)(g))=-85kJ moll^(-1), Delta_(f)H^(@) _(C_(3)H_(8)(g))=-104kJ mol^(-1), DeltaH for C_((s))rarr C_((g)) is 718kJ mol^(-1) and heat of formation of H- atom is 218kJ mol^(-1) , then :

If the heats of formation of C_(2)H_(2) and C_(6)H_(6) are 230 kJ mol^(-1) and 85 kJ mol^(-1) respectively, the DeltaH value for the trimerisation of C_(2)H_(2) is

At 25^(@)C , the following heat of formations are given: {:("Compound",SO_(2)(g),H_(2)O(l),,),(Delta_(f)H^(Theta)kJmol^(-1),-296.0,-285.0,,):} For the reactions at 25^(@)C , 2H_(2)S(g) +Fe(s) rarr FeS_(2)(s) +2H_(2)(g), DeltaH^(Theta) =- 137 kJ mool^(-1) H_(2)S(g) +(3)/(2)O_(2)(g) rarr H_(2)O(l) +So_(2)(g),DeltaH^(Theta) =- 562kJ mol^(-1) Calculate the heat of formation of H_(2)S(g) and FeS_(2)(g) at 25^(@)C .

At 25^(@)C , the following heat of formations are given: {:("Compound",SO_(2)(g),H_(2)O(l),,),(Delta_(f)H^(Theta)kJmol^(-1),-296.0,-285.0,,):} For the reactions at 25^(@)C , 2H_(2)S(g) +Fe(s) rarr FeS_(2)(s) +2H_(2)(g), DeltaH^(Theta) =- 137 kJ mool^(-1) H_(2)S(g) +(3)/(2)O_(2)(g) rarr H_(2)O(l) +So_(2)(g),DeltaH^(Theta) =- 562kJ mol^(-1) Calculate the heat of formation of H_(2)S(g) and FeS_(2)(g) at 25^(@)C .

Delta H_("combustion") of C _(6) H _(6) (l) . C(s) and H _(2) (g) are - 3000 kJ ,-390KJ mol^(-1) and - 290 kJ mol ^(-1) respectively. Hence heat of formation of benzene, is

At 25^(@)C and 1 atm, heat of formation of C_(2)H_(4) (g), CO_(2)(g) and H_(2)O(l) are 52 " kJ mol"^(-1), -394 " kJ mol"^(-1) and -286 " kJ mol"^(-1) respectively. Calculate the heat of combustion of C_(2)H_(4)(g) .

Calculate the resonance enegry of toulene (use Kekule structure form the following data C_(7)H_(8)(l) +9O_(2)(g) rarr 7CO_(2)(g) +4H_(2)O(l)+ DeltaH, DeltaH^(Theta) =- 3910 kJ mol^(-1) C_(7)H_(8)(l) rarr C_(7)H_(8)(g), DeltaH^(Theta) = 38.1 kJ mol^(-1) Delta_(f)H^(Theta) (water) =- 285.8 kJ mol^(-1) Delta_(f)H^(Theta) [CO_(2)(g)] =- 393.5 kJ mol^(-1) Heat of atomisaiton of H_(2)(g) = 436.0 kJ mol^(-1) Heat of sulimation of C(g) = 715.0 kJ mol^(-1) Bond energies of C-H, C-C , and C=C are 413.0, 345.6 , and 610.0 kJ mol^(-1) .

Calculate the resonance energy of toluene (use Kekule structure from the following data C_(7)H_(8)(l) +9O_(2)(g) rarr 7CO_(2)(g) +4H_(2)O(l)+ DeltaH, DeltaH^(Theta) =- 3910 kJ mol^(-1) C_(7)H_(8)(l) rarr C_(7)H_(8)(g), DeltaH^(Theta) = 38.1 kJ mol^(-1) Delta_(f)H^(Theta) (water) =- 285.8 kJ mol^(-1) Delta_(f)H^(Theta) [CO_(2)(g)] =- 393.5 kJ mol^(-1) Heat of atomisation of H_(2)(g) = 436.0 kJ mol^(-1) Heat of sublimation of C(g) = 715.0 kJ mol^(-1) Bond energies of C-H, C-C , and C=C are 413.0, 345.6 , and 610.0 kJ mol^(-1) .

Calculate the enthalpy of formation of Delta_(f)H for C_(2)H_(5)OH from tabulated data and its heat of combustion as represented by the following equaitons: i. H_(2)(g) +(1)/(2)O_(2)(g) rarr H_(2)O(g), DeltaH^(Theta) =- 241.8 kJ mol^(-1) ii. C(s) +O_(2)(g) rarr CO_(2)(g),DeltaH^(Theta) =- 393.5kJ mol^(-1) iii. C_(2)H_(5)OH (l) +3O_(2)(g) rarr 3H_(2)O(g) + 2CO_(2)(g), DeltaH^(Theta) =- 1234.7kJ mol^(-1) a. -2747.1 kJ mol^(-1) b. -277.7 kJ mol^(-1) c. 277.7 kJ mol^(-1) d. 2747.1 kJ mol^(-1)