## Na2S (aq) + 2 HCl (aq) → 2 NaCl (aq) + H2S (g)

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## Stoichiometry

Enter a mass or volume in one of the boxes below. Upon hitting submit, the stoichiometric equivalents will be calculated for the remaining reactants and products. All gases are assumed to be at STP.

 Na2S           Mass: g or Solution Volume: mL of Concentration: mol/L HCl            Mass: g or Solution Volume: mL of Concentration: mol/L NaCl           Mass: g H2S            Mass: g or Gas Volume: L Heat Released: kJ

## Enthalpy of Reaction

[2ΔHf(NaCl (aq)) + 1ΔHf(H2S (g))] - [1ΔHf(Na2S (aq)) + 2ΔHf(HCl (aq))]
[2(-407.25) + 1(-20.17)] - [1(-351.17) + 2(-167.15)] = -149.2 kJ
-149.20 kJ     (exothermic)

## Entropy Change

[2ΔSf(NaCl (aq)) + 1ΔSf(H2S (g))] - [1ΔSf(Na2S (aq)) + 2ΔSf(HCl (aq))]
[2(115.48) + 1(205.77)] - [1(346.07) + 2(56.48)] = -22.3 J/K
-22.30 J/K     (decrease in entropy)

## Free Energy of Reaction (at 298.15 K)

From ΔGf° values:
[2ΔGf(NaCl (aq)) + 1ΔGf(H2S (g))] - [1ΔGf(Na2S (aq)) + 2ΔGf(HCl (aq))]
[2(-393.15) + 1(-33.05)] - [1(-443.72) + 2(-131.25)] = -113.13 kJ
-113.13 kJ     (spontaneous)

From ΔG = ΔH - TΔS:
-142.55 kJ     (spontaneous)

## Equilibrium Constant, K (at 298.15 K)

6.6163936239e+019
This process is favorable at 25°C.

## Reference(s):

Ebbing, Darrell D. General Chemistry 3rd ed.; Houghton Mifflin Company: Boston, MA, 1990; p 87.