Consider the following data. (i) 2Al(s) + 6HCl(aq) Al₂Cl₆(aq) + 3H₂(g) + 1200 kJ/mol (ii) H₂(g) + Cl₂(g) 2HCl(g) + 164 kJ/mol (iii) HCl(g) + aq HCl(aq) + 83 kJ/mol (iv) Al₂Cl₆(s) + aq Al₂Cl₆(aq) + 663 kJ/mol The enthalpy of formation of anhydrous solid Al₂Cl₆ is :

Step-by-step solution

The given reactions with their enthalpy changes are: (i) 2Al(s) + 6HCl(aq) Al₂Cl₆(aq) + 3H₂(g) , H₁ = -1200 kJ/mol (ii) H₂(g) + Cl₂(g) 2HCl(g) , H₂ = -164 kJ/mol (iii) HCl(g) + aq HCl(aq) , H₃ = -83 kJ/mol (iv) Al₂Cl₆(s) + aq Al₂Cl₆(aq) , H₄ = -663 kJ/mol The required reaction for the enthalpy of formation of anhydrous solid Al₂Cl₆ is: 2Al(s) + 3Cl₂(g) Al₂Cl₆(s) This target equation can be obtained by applying the following algebraic operations on the given equations: Equation (i) + 3 Equation (ii) + 6 Equation (ii