Pb(NO3)2 (aq) + 2 NaBr (aq) → PbBr2 (s) + 2 NaNO3 (aq)

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Reaction Type:

Double Displacement

Stoichiometry

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Pb(NO3)2       Mass: g  or Solution Volume: mL of Concentration: mol/L
NaBr           Mass: g  or Solution Volume: mL of Concentration: mol/L
PbBr2          Mass: g
NaNO3          Mass: g  or Solution Volume: mL of Concentration: mol/L

Enthalpy of Reaction

[1ΔHf(PbBr2 (s)) + 2ΔHf(NaNO3 (aq))] - [1ΔHf(Pb(NO3)2 (aq)) + 2ΔHf(NaBr (aq))]
[1(-277.4) + 2(-447.46)] - [1(-416.42) + 2(-361.65)] = -32.6000000000001 kJ
-32.60 kJ     (exothermic)

Entropy Change

[1ΔSf(PbBr2 (s)) + 2ΔSf(NaNO3 (aq))] - [1ΔSf(Pb(NO3)2 (aq)) + 2ΔSf(NaBr (aq))]
[1(161.13) + 2(205.44)] - [1(303.38) + 2(141.42)] = -14.21 J/K
-14.21 J/K     (decrease in entropy)

Free Energy of Reaction (at 298.15 K)

From ΔGf° values:
[1ΔGf(PbBr2 (s)) + 2ΔGf(NaNO3 (aq))] - [1ΔGf(Pb(NO3)2 (aq)) + 2ΔGf(NaBr (aq))]
[1(-260.75) + 2(-373.24)] - [1(-247.08) + 2(-365.87)] = -28.41 kJ
-28.41 kJ     (spontaneous)

From ΔG = ΔH - TΔS:
-28.36 kJ     (spontaneous)

Equilibrium Constant, K (at 298.15 K)

94949.7028900009
This process is favorable at 25°C.

Reference(s):

Ebbing, Darrell D. General Chemistry 3rd ed.; Houghton Mifflin Company: Boston, MA, 1990; p 98.

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