Solvent Effects on the Energetics of Reactions

3 Solvent effects on the energetics of reactions f Coor /.C/iem. ev.31(1980)93) When the kinetics of a reaction is studied in water and this is compared to the situation where water is partially or completely replaced by another (usually organic) solvent, the energetics of the reaction change depending on the effect of the solvents on the 

4 Energetics of the persulphate oxidation of the complex in water/ethanol mixtures 

Repeat the runs in Sec. 13.7.2 using at least two ethanol/water mixtures eg 2S% and 50% ethanol (v/v). Calculate in each case AG,ct and hence work out 6AG,ct for the solvent mixtures. 

Alternatively record the u.v. spectrum of a 5 x 10 M solution of the salt in the ethanol/water mixture and determine the wavelength of maximum absorption. Prepare at least three other solutions of various concentrations. Plot absorbance at the determined wavelength against concentration. Use the plot to calculate the concentration of the saturated solution. 

Prepare a stock solution of 5 x 10 M in the complex in water. By dilution, prepare at least three solutions with other concentrations. Measure the absorbance at the wavelength of maximum absorption for the solutions. Plot absorbance against concentration and work out e in m mof. Prepare a saturated solution of the complex in water by sonicating a concentrated solution for 30 minutes after adding more solid until a residue remains undissolved at 25°C. Measure the absorbance of the supernatant at the same wavelength and hence calculate the solubility at 25 C. 

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