Consider the reaction 2 H _2 S (g) + 3 O _2(g) 2 H _2 O (l) + 2 SO _2(g) The magnitude of enthalpy change for the reaction in kJ mol^ -1 is ________. (Nearest integer) Given: _fH^ ( H _2 S ) = -20.1 kJ mol^ -1 _fH^ ( H _2 O ) = -286.0 kJ mol^ -1 _fH^ ( SO _2) = -297.0 kJ mol^ -1
A. A
The standard enthalpy of reaction is given by: _r H^ = _f H^ ( products ) - _f H^ ( reactants ) For the given reaction: 2 H _2 S (g) + 3 O _2(g) 2 H _2 O (l) + 2 SO _2(g) _r H^ = [2 _f H^ ( H _2 O , l) + 2 _f H^ ( SO _2, g)] - [2 _f H^ ( H _2 S , g) + 3 _f H^ ( O _2, g)] Substituting the given values: _r H^ = [2(-286.0) + 2(-297.0)] - [2(-20.1) + 3(0)] _r H^ = [-572.0 - 594.0] - [-40.2] _r H^ = -1166.0 + 40.2 = -1125.8 kJ mol ^ -1 The magnitude of the enthalpy change is 1125.8 kJ mol ^ -1 . Rounding to the nearest integer, we get 1126. Answer: 1126
Related: Chemistry — Thermodynamics (C) · All PYQ Banks