A-LevelChemistryGroup 2May/June 2017Paper 4 Q113 Marks
The table lists the standard enthalpy changes of formation, ΔH, for some compounds and aqueous ions. | species | ΔHᶠ/kJ mol⁻¹ | |------------|-------------| | Ba²⁺(aq) | -538 | | OH⁻(aq) | -230 | | CO₂(g) | -394 | | BaCO₃(s) | -1216 | | H₂O(l) | -286 | If CO₂(g) is bubbled through an aqueous solution of Ba(OH)₂ for a long time, the precipitated BaCO₃(s) dissolves, as shown in reaction 2. BaCO₃(s) + CO₂(g) + H₂O(l) → Ba(HCO₃)₂(aq) reaction 2 The standard enthalpy change for reaction 2, ΔHᵣ₂ = −26 kJ mol⁻¹.
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