Question

Calculate the entropy change for the combustion of methane at a constant temperature and pressure of 298 K and 1 atm, respectively. The balanced equation for the reaction is:CH4(g) + 2O2(g) → CO2(g) + 2H2O(l)

Answer 1

To calculate the entropy change  S  for the combustion of methane, we need to find the difference in entropy between the products and reactants at the given temperature and pressure. We can use the standard molar entropies  S  of each substance involved in the reaction.The standard molar entropies at 298 K are as follows:S CH4, g  = 186.3 J/molKS O2, g  = 205.2 J/molKS CO2, g  = 213.8 J/molKS H2O, l  = 69.95 J/molKNow, we can calculate the entropy change  S  using the equation:S = S products  - S reactants S = [1  S CO2, g  + 2  S H2O, l ] - [1  S CH4, g  + 2  S O2, g ]S = [1  213.8 J/molK + 2  69.95 J/molK] - [1  186.3 J/molK + 2  205.2 J/molK]S = [213.8 + 139.9] - [186.3 + 410.4]S = 353.7 - 596.7S = -243 J/molKThe entropy change for the combustion of methane at 298 K and 1 atm is -243 J/molK.