Calculate the enthalpy of formation (in kcal/mol) of anhydrous Al2Cl6 from the following data: 2Al(s) + 6(aq) - Al2Cl6(aq) + 3(g); δ H = -239.760 kcal; (g) + (g) - 2(g); δ H = -44 kcal; (g) + aq -

Question

Calculate the enthalpy of formation (in kcal/mol) of anhydrous Al2Cl6 from the following data: 2Al(s) + 6$HCl$(aq) -> Al2Cl6(aq) + 3$H_2$(g); δ H = -239.760 kcal; $H_2$(g) + $Cl_2$(g) -> 2$HCl$(g); δ H = -44 kcal; $HCl$(g) + aq -> $HCl$(aq); δ H = -17.315 kcal; Al2Cl6(s) + aq -> Al2Cl6(aq); δ H = -153.690 kcal

Prashant Kotian · Accepted Answer

Correct answer: B. Target: 2Al(s) + 3(g) -> Al2Cl6(s). Combine: (1) dH = -239.76; (2) 3(g) + 3(g) -> 6(g) dH = -132; (3) 6(g) + aq -> 6(aq) dH = -103.89; (4) Al2Cl6(aq) -> Al2Cl6(s) + aq dH = +153.69. Sum: delta_f H = -239.76 - 132 - 103.89 + 153.69 = -321.960 kcal/mol.

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