Objective Problems

In which case is a reaction possible at any temperature?

In which case is a reaction impossible at any temperature?

The difference between the heat of reaction at constant pressure and constant volume for the reaction: $2{\mathrm{C}}_6{\mathrm{H}}_6 \left(\mathrm{l}\right)+15{\mathrm{O}}_2 \left(\mathrm{g}\right)\to 12{\mathrm{CO}}_2 \left(\mathrm{g}\right)+6{\mathrm{H}}_2\mathrm{O} \left(\mathrm{l}\right)$ at $25°\mathrm{C}$ in $\mathrm{kJ}$ is:

The molar heat capacity of water in equilibrium with ice at constant pressure is:

Standard molar enthalpy of formation of ${\mathrm{CO}}_2$ is equal to:

When steam condenses to water at $90°\mathrm{C}$, the entropy of the system decreases. What must be true if the second law of thermodynamics is to be satisfied?

[Hint: For a spontaneous process ${\mathrm{\Delta S}}_{\text{universe}}$ must be positive.]

A certain reaction is spontaneous at $85°\mathrm{C}$. The reaction is endothermic by $34 \mathrm{kJ}$. The minimum value of $\mathrm{\Delta S}$ for the reaction is:

For the reaction, $\frac{1}{2}{\mathrm{A}}_2+\frac{1}{2}{\mathrm{B}}_2\to \mathrm{AB}; \mathrm{\Delta H}=-50 \mathrm{kcal}$.

If the bond energies of ${\mathrm{A}}_2, {\mathrm{B}}_2$ and $\mathrm{AB}$ are $\mathrm{x}, \frac{\mathrm{x}}{2}$ and $\mathrm{x} \mathrm{kcal}$, respectively, the value of $\mathrm{x}$ is: