1. The problem statement, all variables and given/known data at 25C & 1 atm, absolute entropy of methane and ethane are 186.19 J/K/mol and 229.49 J/K/mol in gas phase. Find absolute 3rd law entropy of a solution containing 1 mol of each gas in ideal behavior. 2. Relevant equations I think this is the equation to use: dSmix= -nR(x1lnx1 + x2lnx2) where x1 and x2 i can find from 1 mole of each gas (mole fractions) if i use this equation, then the absolute entropy of methane and ethane woud be useless in this equation. or is there another way of solving it with the absolute entropies? Thanks in advance.