Question

Be sure to answer all parts find the value of S . Report the value with the appropriate sign.

(a) 3 NO2( g ) + H2O( l ) 2 HNO3( l ) + NO( g ) J/K

(b) N2( g ) + 3 F2( g ) 2 NF3( g ) J/K

(c) C6H12O6( s ) + 6 O2( g ) 6 CO2( g ) + 6 H2O( g ) J/K

Answer 1

(a) delS⁰_rxn = Sum of S⁰_{products -} Sum of S⁰_reactants

              ₌ [2*S⁰ (HNO3) + S⁰ (NO) ] - [[3 * S⁰ (NO2) + S⁰ (H2O) ]

        = [2 * 155.6 + 210.7] - [3 * 240.0 + 69.9]

           = [ 521.9] - [789.9] = -268 J/K mol

(b) delS⁰_rxn = Sum of S⁰_{products -} Sum of S⁰_reactants

             = [2 * S⁰ (NF3)] - [S⁰(N2) + 3 * S⁰ (F2)]

           = [2* 260.7] - [191.5 + 3 * 202.7] = [521.4 ] - [799.6] = - 278.2 J/K mol

(c) delS⁰_rxn = Sum of S⁰_{products -} Sum of S⁰_reactants

         ₌ [ 6 * S⁰(CO2) + 6 * S⁰(H2O)] - [S⁰ (C6H12O6) + 6 * S⁰ (O2)]

      = [6 * 213.7 + 6 * 188.7] - [209.2 + 6 * 205.0] = [1282.2 + 1132.2] - [209.2 + 1230]

                                                          = 2414.4 - 1439.2 = 975.2 J/K mol