Chapter 18, Problem 18.68QP

The combustion of acetylene, C₂H₂, is a spontaneous reaction given by the equation

$2{\text{C}}_2{\text{H}}_2(g)+5{\text{O}}_2(g)\stackrel{}{\to }4{\text{CO}}_2(g)+2{\text{H}}_2\text{O}(l)$

As expected for a combustion, the reaction is exothermic. What is the sign of ΔH°? What do you expect for the sign of ΔS°? Explain the spontaneity of the reaction in terms of the enthalpy and entropy changes.