1. Chem 1310: Introduction to physical chemistry Part 2: exercises 27, p659 Hydrolysis of benzenesulfonyl chloride

2. C 6 H 5 SO 2 Cl + H 2 O  C 6 H 5 SO 3 H + H + + Cl - in the presence of F - F - does not occur in the reaction equation. Looks like it is a catalyst.

3. Hydrolysis of benzenesulfonyl chloride Some reaction occurs even without F -. We need to correct for that. [F - ]Initial rate mol/Lmol L -1 s -1 0.0002.40E-07 0.0055.40E-07 0.0107.90E-07 0.0201.39E-06 0.0302.02E-06 0.0402.52E-06 0.0503.20E-06 Test: rate(0.05)/rate(0.01) = 4.05 rate(0.01)/rate(0.005) = 1.46 Not cleanly first-order (or any order)

4. Hydrolysis of benzenesulfonyl chloride rate F = k F [F - ] Calculated k F = 5.80*10 -5 s -1. [F - ]Initial rateCorr initial rate mol/Lmol L -1 s -1 0.0002.40E-070 0.0055.40E-073.00E-07 0.0107.90E-075.50E-07 0.0201.39E-061.15E-06 0.0302.02E-061.78E-06 0.0402.52E-062.28E-06 0.0503.20E-062.96E-06 Test again: rate(0.05)/rate(0.01) = 5.38 rate(0.01)/rate(0.005) = 1.83 This looks a bit better

5. Hydrolysis of benzenesulfonyl chloride Given that the whole reaction is first-order in [C 6 H 5 SO 2 Cl], can we now construct a rate law? We have assumed that the [F - ]-independent part is constant, so the total rate is k 0 + k F [F - ] with k 0 = 2.40*10 -7 mol L -1 s -1 and k F = 5.80*10 -5 s -1.

6. Hydrolysis of benzenesulfonyl chloride This was at [C 6 H 5 SO 2 Cl] = 2.0*10 -4 mol L -1. At different concentrations, we must have:

7. Hydrolysis of benzenesulfonyl chloride How does this relate to the reaction mechanism? UnassistedF - -assisted