(c) For the spreading of the oil C16H34 over water, at constant temperature and pressure, a small change in the surface free energy of the system is given by the total differential: ag aG ag dG = |dAA+ VAA Como la AAB dAAB+ d AB a AB Knowing that the values of the surface tensions are: Y water 72.8 mNm 7 C16H34 - 30.0 mNm- Y C16H34 water - 52.1 mNm-! derive from the above equation an expression for the spreading coefficient and calculate the spreading coefficient for CH 34 on water. [4 marks) (d) Consider a crystal of toluene. Estimate the residual entropy of 1 mol of crystal assuming the methyl group can occupy any position in the aromatic ring. [5 marks)