To calculate the Gibbs free energy change G for the reaction NH3 g + HCl g NH4Cl s at standard conditions 298 K and 1 atm , we need to follow these steps:1. Determine the standard enthalpy change H and standard entropy change S for the reaction.2. Use the Gibbs free energy equation: G = H - TS, where T is the temperature in Kelvin.Step 1: Determine H and STo determine the standard enthalpy change H and standard entropy change S for the reaction, we need to use the standard enthalpies of formation Hf and standard molar entropies S of the reactants and products. These values can be found in standard thermodynamic tables or calculated using quantum chemistry calculations.For this problem, we will assume that the values are given as follows in kJ/mol for Hf and J/molK for S :NH3 g : Hf = -45.9 kJ/mol, S = 192.5 J/molKHCl g : Hf = -92.3 kJ/mol, S = 186.9 J/molKNH4Cl s : Hf = -314.4 kJ/mol, S = 94.6 J/molKNow, we can calculate H and S for the reaction:H = [Hf NH4Cl - Hf NH3 - Hf HCl ] = [-314.4 - -45.9 - -92.3 ] kJ/mol = -176.2 kJ/molS = [S NH4Cl - S NH3 - S HCl ] = [94.6 - 192.5 - 186.9] J/molK = -284.8 J/molKStep 2: Calculate G using the Gibbs free energy equationNow that we have H and S, we can calculate G using the Gibbs free energy equation:G = H - TSAt standard conditions, T = 298 K. Make sure to convert S to kJ/molK by dividing by 1000:G = -176.2 kJ/mol - 298 K -284.8 J/molK / 1000 = -176.2 kJ/mol + 84.9 kJ/mol = -91.3 kJ/molSo, the Gibbs free energy change G for the reaction NH3 g + HCl g NH4Cl s at standard conditions 298 K and 1 atm is -91.3 kJ/mol.