AIEEE 2006 | Thermodynamics Question 166 | Chemistry

The standard enthalpy of formation $$\Delta _fH^o$$ at 298 K for methane, CH₄(g), is –74.8 kJ mol^–1. The additional information required to determine the average energy for C – H bond formation would be :

the dissociation energy of H₂ and enthalpy of sublimation of carbon

latent heat of vapourization of methane

the first four ionization energies of carbon and electron gain enthalpy of hydrogen

the dissociation energy of hydrogen molecule, H₂

AIEEE 2005

MCQ (Single Correct Answer)

-1

Consider the reaction: N₂ + 3H₂ $$\to$$ 2NH₃ carried out at constant temperature and pressure. If $$\Delta H$$ and $$\Delta U$$ are the enthalpy and internal energy changes for the reaction, which of the following expressions is true?

$$\Delta H$$ > $$\Delta U$$

$$\Delta H$$ < $$\Delta U$$

$$\Delta H$$ = $$\Delta U$$

$$\Delta H$$ = 0

AIEEE 2005

MCQ (Single Correct Answer)

-1

If the bond dissociation energies of XY, X₂ and Y₂ (all diatomic molecules) are in the ratio of 1:1:0.5 and $$\Delta H_f$$ for the formation of XY is -200 kJ mole^-1. The bond dissociation energy of X₂ will be :

100 kJ mol^-1

200 kJ mol^-1

300 kJ mol^-1

800 kJ mol^-1

AIEEE 2005

MCQ (Single Correct Answer)

-1

Consider an endothermic reaction, X $$\to$$ Y with the activation energies E_b and E_f for the backward and forward reactions, respectively. In general :

E_b < E_f

E_b > E_f

E_b = E_f

There is no definite relation between E_b and E_f

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