Calculate the Gibbs free energy change at 298 K for the reaction of hydrogen gas (H2) and chlorine gas (Cl2) to form hydrogen chloride gas (2HCl), given the following thermodynamic data:∆H°f (HCl) = -92.31 kJ/mol∆H°f (H2) = 0 kJ/mol∆H°f (Cl2) = 0 kJ/mol∆S°f (HCl) = -181.6 J/(mol*K)∆S°f (H2) = 130.7 J/(mol*K)∆S°f (Cl2) = 223.1 J/(mol*K)Also, determine whether the reaction is spontaneous at 298 K and if it will shift towards products or reactants.

Question

Calculate the Gibbs free energy change at 298 K for the reaction of hydrogen gas (H2) and chlorine gas (Cl2) to form hydrogen chloride gas (2HCl), given the following thermodynamic data:∆H°f (HCl) = -92.31 kJ/mol∆H°f (H2) = 0 kJ/mol∆H°f (Cl2) = 0 kJ/mol∆S°f (HCl) = -181.6 J/(mol*K)∆S°f (H2) = 130.7 J/(mol*K)∆S°f (Cl2) = 223.1 J/(mol*K)Also, determine whether the reaction is spontaneous at 298 K

Answer 1

To calculate the Gibbs free energy change  G  for the reaction, we can use the equation:G = H - TSFirst, we need to find the enthalpy change  H  and the entropy change  S  for the reaction.The balanced chemical equation for the reaction is:H2 g  + Cl2 g   2HCl g H for the reaction can be calculated using the enthalpies of formation  Hf  of the products and reactants:H = [2 * Hf HCl ] - [Hf H2  + Hf Cl2 ]H = [2 *  -92.31 kJ/mol ] - [0 + 0]H = -184.62 kJ/molNext, we need to calculate the entropy change  S  for the reaction using the standard molar entropies  Sf  of the products and reactants:S = [2 * Sf HCl ] - [Sf H2  + Sf Cl2 ]S = [2 *  -181.6 J/ mol*K  ] - [130.7 J/ mol*K  + 223.1 J/ mol*K ]S =  -363.2 J/ mol*K   -  353.8 J/ mol*K  S = -717 J/ mol*K Now, we can calculate the Gibbs free energy change  G  at 298 K:G = H - TSG = -184.62 kJ/mol -  298 K *  -717 J/ mol*K   *  1 kJ/1000 J  G = -184.62 kJ/mol +  298 K * 0.717 kJ/ mol*K  G = -184.62 kJ/mol + 213.66 kJ/molG = 29.04 kJ/molThe Gibbs free energy change  G  for the reaction at 298 K is 29.04 kJ/mol. Since G is positive, the reaction is not spontaneous at 298 K, and it will shift towards reactants.