Question

ΔG(T,P)= ΔG°(T)+RTlnQ(T,P)

-RTlnK(T)=ΔG°(T)=ΔH°(T)-TΔS°(T)

H2(g)+1/2 S2 (g) <=> H2S(g)

1. determine the value of the standard enthalpy change of the reaction ΔH°and its uncertainty

2. determine the value of the standard entropy change of the reaction ΔS° and its uncertainty

3. give the value of the equilibrium constant at 1000°C

T(°c) = 750 830 945 1065 1089 1132 1200 1264 1394

K = 106.2 45.0 23.5 8.9 8.2 6.2 5.0 3.2 1.6

Answer 1

      H2(g)+1/2 S2 (g) <=> H2S(g)

DH0rxn = DH0H2S - (1/2*DH0s2 + DH0H2)

       = (-20.6) - (1/2*0 + 0)

       = -20.6 kj/mol

DS0rxn = S0H2S - (1/2*S0S2+S0H2)

       = (205.7) - (32.054+130.6)

       = 43.046 j/k.mol

DG0 = DH0-TDS0

     = (-20.6*10^3)-1273.15*43.046

     = -75.404 kj/mol

DG0 = - RTlnk

-75404 = -8.314*1273.15lnk

   k = 1.241*10^3