Question

Calculate the standard enthalpy of formation of Cl⁻(aq), using the provided thermochemical data at 1 bar. Given that the standard enthalpies of formation of H₂(g) and H⁺(aq) are both zero.

HCl(g) → H⁺(aq) + Cl⁻(aq)ΔH=−75.15kJ

Cl₂(g) → 2HCl(g)ΔH=−184.62kJ

Answer 1

To calculate the standard enthalpy of formation of Cl⁻(aq), we can use Hess's Law and the given thermochemical data. By summing the reactions, we determine that the standard enthalpy of formation of Cl⁻(aq) is -184.62 kJ/mol.

Step-by-step explanation:

To calculate the standard enthalpy of formation of Cl⁻(aq), we can use Hess's Law. We are given that the standard enthalpy of formation of H₂(g) and H⁺(aq) are both zero. We also have the thermochemical data for the reactions:

HCl(g) → H⁺(aq) + Cl⁻(aq) ΔH = -75.15 kJ
Cl₂(g) → 2HCl(g) ΔH = -184.62 kJ

Using these equations, we can determine the standard enthalpy of formation of Cl⁻(aq). By summing the reactions, we get:

Cl₂(g) + H₂(g) → 2H⁺(aq) + 2Cl⁻(aq) ΔH = -184.62 kJ - (2 x 0) kJ
Cl₂(g) + H₂(g) → 2H⁺(aq) + 2Cl⁻(aq) ΔH = -184.62 kJ

Therefore, the standard enthalpy of formation of Cl⁻(aq) is -184.62 kJ/mol.