Long homework due in one week after completion of Chapter 3
Chapter 3, Background Thermodynamics. Envr. 210
1.
An organic liquid is equilibrated with pure water in a stoppered flask:
organic
phase
aqueous
phase
(a) Assuming that the organic liquid consists of pure toluene (molecular weight
92.13, density 0.8669, aqueous solubility 515 mg/L at 25C), what is:
(i) the concentration of toluene in the aqueous phase in mol/L and in mole
fraction units;
(ii) the aqueous activity coefficient and the activity of toluene in the aqueous
phase (neglect any dissolution of water in the organic phase).
(iii) the mole fraction based equilibrium constant K'12 for the dissolution
process and the concentration based equilibrium constant K12;
(iv) the partial molar excess free energy of solution of toluene in the aqueous
phase as well as in the organic phase at 25C;
(b)
Now assume that instead of consisting of pure toluene, the organic phase
consists of a 50:50 (volume: volume) mixture of benzene (molecular
weight 78.11, density 0.88765) and toluene. What will be the
concentration of toluene in the aqueous phase (in mol/L) assuming that
nonideal interactions are (to a first approximation) independent of
concentration?
2. Derive a relationship for a generic equilibrium const. ,Keq as a function of free
energy G
3. Derive an expression for Keq as a function of temperature