HCN (aq) + 1 KOH (aq) → KCN (aq) + H2O (ℓ)

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Reaction Type:

Double Displacement

Stoichiometry

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HCN            Mass: g  or Solution Volume: mL of Concentration: mol/L
KOH            Mass: g  or Solution Volume: mL of Concentration: mol/L
KCN            Mass: g
H2O            Mass: g
Heat Released: kJ

Enthalpy of Reaction

[1ΔHf(KCN (aq)) + 1ΔHf(H2O (ℓ))] - [1ΔHf(HCN (aq)) + 1ΔHf(KOH (aq))]
[1(-191.73) + 1(-285.83)] - [1(60.67) + 1(-482.39)] = -55.84 kJ
-55.84 kJ     (exothermic)

Entropy Change

[1ΔSf(KCN (aq)) + 1ΔSf(H2O (ℓ))] - [1ΔSf(HCN (aq)) + 1ΔSf(KOH (aq))]
[1(298.31) + 1(69.91)] - [1(195.81) + 1(91.75)] = 80.66 J/K
80.66 J/K     (increase in entropy)

Free Energy of Reaction (at 298.15 K)

From ΔGf° values:
[1ΔGf(KCN (aq)) + 1ΔGf(H2O (ℓ))] - [1ΔGf(HCN (aq)) + 1ΔGf(KOH (aq))]
[1(-244.56) + 1(-237.18)] - [1(38.74) + 1(-440.58)] = -79.9 kJ
-79.90 kJ     (spontaneous)

From ΔG = ΔH - TΔS:
-79.89 kJ     (spontaneous)

Equilibrium Constant, K (at 298.15 K)

9.969038464e+013
This process is favorable at 25°C.

Reference(s):

Ebbing, Darrell D. General Chemistry 3rd ed.; Houghton Mifflin Company: Boston, MA, 1990; p 90.

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