Question

2) One of the reactions for today's class was the dissolution of solid sodium chloride. NaCl (s) = Nat (aq) + CI (aq) Use the data from the table to calculate: Substance NaCl (s) Nat (aq) ci" (aq) Hiº (kJ/mol) S (J/mol K) AG (kJ/mol) -411.2 72.13 -384.1 -239.66 60.25 -261.87 -167. 2 5 6.5 -131.2 229 66 1 A) AH RXN B) AS RXN C) AGⓇAXN D) The little circle which looks like the degree symbol (º) is used to indicate standard conditions which are defined as: pressure = 1 atm; temperature = 25 °C; solution concentration = 1 M. According to your calculations, is the dissolution of NaCl (s) spontaneous under standard conditions?

Answer 1

A) ∆H° = total enthalpy of formation of products - enthalpy of formation of reactants

∆H°= ( -239.66-167.2)-(-411.2)

=> 4.34 kJ/mol

B) ∆S° = 56.5+60.25-72.13 => 44.62 J/mol-k

C) ∆G° =( -131.2-261.87) - (-384.1)

= -8.97 kJ/mol

D) as ∆G° is negative , it is spontaneous reaction.