Entropy Quiz 7

1
Entropy Quiz 7 Consider the decomposition of
solid ammonium chloride, NH4Cl (s) at 1 bar and
298.2 K 298.2 K NH4Cl
(s) -----gt NH3 (g) HCl (g) ?Ho298 K
176 kJ 1 bar Assume this reaction
occurs while in thermal contact with an infinite
surroundings at 298.2 K. This reaction is at
equilibrium at 619 K when the pressure is 1
bar. For this reaction at 1 bar and 298.2 K give
the sign on the following quantities ?So298 K,
system gt 0 The gaseous products are much
more disordered than the solid reactant. ?So298
K, surroundings lt 0 The endothermic reaction
absorbs heat from the surroundings and, as a
result, the entropy of the isothermal
surroundings decreases. ?So298 K, total lt 0 At
1 bar and 298.2 K, NH4Cl (s) is stable relative
to the products and the reaction under these
conditions is spontaneous in the direction of the
reactants. Since this is the opposite of the
reaction arrow, the total entropy change is
negative.