Question

The combustion of octane, $C_8{H}_{18}$, has $\Delta H_{reaction}^{\circ }<0$ and $\Delta S_{reaction}^{\circ }>0$.
Regarding the combustion of octane, which of the following statements is wrong?

• A. The reaction is spontaneous at room temperature.
• B. The reaction is spontaneous at all temperatures.
• C. The reaction products are carbon dioxide and water vapor.
• D. The reaction is a redox process.
• E. The reaction is endothermic at room temperature.

Answer 1

The correct option is E The reaction is endothermic at room temperature.

The negative value of the standard enthalpy change $\Delta H_{reaction}^{\circ }$ for the reaction indicates that the reaction is exothermic at room temperature. The enthalpy of reactants is higher than the enthalpy of products. The difference is given out as heat.