Enthalpy, Entropy, and Free Energy Answers

Indicate whether each of these reactions is endothermic or exothermic.NH4Cl(s) NH4+(aq) + Cl–(aq) Hrxn = 14.7 kJ

NaOH(s) Na+(aq) + OH–(aq) Hrxn = -44.5 kJ

CH4(g) + 2O2(g) CO2(g) + 2H2O(g) Hrxn < 0

CH3COOH(aq) + NaHCO3(s) CO2(g) + H2O(l) + Na+(aq) + CH3COO–(aq) Hrxn > 0

These reactions are all spontaneous. Based on this information, is enthalpy of reaction a reliable indicator of whether a reaction is spontaneous?