Using Solubility RulesClassify these ionic compounds as

Entropy Changes & Spontaneity methane from gas leak in LA reacts with O2 in atmosphere and combusts to form • water and CO2 —CH4(g) + 2O2(g)—>CO2(g) + 2H2O(l) —3 gas molecules—> 1 gas molecule + 2 liquid molecules results in decrease in entropy • ∆Ssys=∆Hsys/T • ∆Ssurr=∆Hsurr/T • ∆Suniv=∆Ssys + ∆Ssurr = ∆Ssys - (∆Hsys/T) • ex. Calculate ∆Ssys, ∆Ssurr, and ∆Suniv when 1 mole of water in ice at 0˚C melts to 22˚C. ∆H=6.01 kJ —∆Ssys=6010 J/273 K=22.0 J/K —∆Ssurr=-6010 J/295 K=-20.4 J/K —∆Suniv=22.0 J/K - 20.4 J/K=1.6 J/K • if ∆Suniv>0, the reaction is spontaneous —only ∆Suniv can determine spontaneity, not ∆Ssys (determines # microstates) • ∆Srxn=(#moles x ∆S) products - (#moles x ∆S) reactants • Gibbs free energy formula —∆Gsys=∆Hsys - T∆Ssys • spontaneity of a reaction —if ∆Gsys<0, then ∆Suniv>0 and the reaction is spontaneous —if ∆Gsys>0, then ∆Suniv<0 and the reaction is non spontaneous (no reaction) —if ∆Gsys=0, then ∆Suniv=0 and the reaction has reached chemical equilibrium (forward and reverse reactions occur at the same rate) • spontaneous reactions are not always exothermic • type of thermic reaction determined by enthalpy —if ∆Hsys>0, the reaction is endothermic —if ∆Hsys<0, the reaction is exothermic T∆S Energy Right side ∆G<0—>spontaneous ∆H Temp