Question

On passing benzene vapours through a tube at \[700-800{}^\circ C\] or through molten lead we get
A.Diphenyl.
B.Phenol.
C.Toluene.
D.Benzaldehyde.

Answer 1

Hint: We know that enthalpy is a state function, which means, the change in enthalpy in a given process will only depend on its initial and final stages and not how the process occurred. That means, in a given chemical reaction, the enthalpy change can be simply calculated if we take the enthalpy of formation of all the reactants and products into account. That is what we are going to ask in this question.

Complete answer:
An ideal solution is a blend wherein the molecules of various species are recognizable, however, in contrast to the ideal gas; the molecules in ideal solution apply force on each other. Raoult's law expresses that the vapor pressure of a solvent over a solution is equivalent to the vapor pressure of the pure solvent at a similar temperature scaled by the mole fraction of the solvent present.

Therefore, the correct answer is option A.

Additional Information:
In this case, the reactant is ethyne molecule and the product is benzene molecule. According to the stoichiometric coefficients in the chemical reaction, three molecules of ethyne react to form one molecule of benzene. Therefore, the standard change in enthalpy of formation of ethyne will be multiplied by three while that of benzene will be multiplied by one.

Note:
Remember that It is essential to indicate the temperature while stating a vapor pressure since vapor pressures increment with temperature. Also, know that there are a few different units for pressure. The most widely recognized unit for vapor pressure.