Chemistry 112

Find the standard enthalpy of reaction between solid aluminum sulfate and aqueous sodium hydroxide.

Al₂(SO₄)₃(s) + 6 NaOH(aq) → 2 Al(OH)₃(s) + 6 Na⁺(aq) + 3 SO₄^2–(aq)

ΔH^o = [2ΔH_f^o (Al(OH)₃(s)) + 6ΔH_f^o (Na⁺(aq) + 3ΔH_f^o (SO₄^2–(aq))]
– [ΔH_f^o (Al₂(SO₄)₃(s)) + 6ΔH_f^o (NaOH(aq))]

Looking the enthalpies of formation from the Table of Thermodynamic quantities:

ΔH^o = [2(–1276) + 6(–240.1) + 3(–909.3)] – [–3441 + 6(–469.2)] = –464 kJ/mol

The reaction is exothermic.

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