Question

Using the data provided in the Table, calculate the various entropies below for

H₂S(aq) $LaTeX: \longrightarrow$ ⟶ H⁺(aq) + HS^-(aq)

Enter your numbers to 1 decimal places.

substance or Ion	$LaTeX: \Delta$ ΔH°f (kJ/mol)	S° (J/mol K)
H2S(aq)	-39	122
H+(aq)	0	0
HS-(aq)	-17.7	61.1

1. Calculate ΔS_system (J/K)
2. Calculate ΔS_surrouding (J/K)
3. Calculate ΔS_univ (J/K)

Answer 1

$\Delta$S_system = S^o products - S^o reactants

$\Delta$S_system = [S^o H⁺ (aq) + S^o HS^- (aq)] - S^o H₂S (aq)

$\Delta$S_system = [0 + 61.1 J/mol-K] - (122 J/mol-K)

$\Delta$S_system = 61.1 J/K - 122 J/K

$\Delta$S_system = -60.9 J/K

$\Delta$H = $\Delta$ H^o_f products - $\Delta$ H^o_f reactants

$\Delta$H = [$\Delta$H^o_f H⁺ (aq) + $\Delta$ H^o_f HS^- (aq)] - $\Delta$ H^o_f H₂S (aq)

$\Delta$H = (0 + (-17.7 kJ/mol)) - (-39 kJ/mol)

$\Delta$H = 21.3 kJ = 21300 J

$\Delta$H_surrounding = -($\Delta$H_system)

$\Delta$H_surrounding = -(21300 J)

$\Delta$H_surrounding = -21300 J

$\Delta$S_surrounding = ($\Delta$H_surrounding) / (T)

$\Delta$S_surrounding = (-21300 J) / (298 K)

$\Delta$S_surrounding = -71.5 J/K

$\Delta$S_univ = ($\Delta$S_system) + ($\Delta$S_surrounding)

$\Delta$S_univ = (-60.9 J/K) + (-71.5 J/K)

$\Delta$S_univ = -132.4 J/K

$\Delta$S_univ =