Question

Calculate the standard molar entropy change for the reaction: 2 SO2(g) + O2(g) → 2 SO3(g) at 298 K, given the following standard molar entropies: ΔS°(SO2(g)) = 248.2 J K^-1 mol^-1 ΔS°(O2(g)) = 205.0 J K^-1 mol^-1 ΔS°(SO3(g)) = 256.2 J K^-1 mol^-1

Answer 1

To calculate the standard molar entropy change  S  for the reaction, we can use the following equation:S reaction  =  S products  -  S reactants For this reaction, we have:S reaction  = [2  S SO3 g  ] - [2  S SO2 g   + S O2 g  ]Now, we can plug in the given standard molar entropies:S reaction  = [2  256.2 J K^-1 mol^-1] - [2  248.2 J K^-1 mol^-1 + 205.0 J K^-1 mol^-1]S reaction  = [512.4 J K^-1 mol^-1] - [496.4 J K^-1 mol^-1 + 205.0 J K^-1 mol^-1]S reaction  = 512.4 J K^-1 mol^-1 - 701.4 J K^-1 mol^-1S reaction  = -189.0 J K^-1 mol^-1The standard molar entropy change for the reaction is -189.0 J K^-1 mol^-1.