Question

89.5* M. Cyfert, et al. (Int. J. Chem. Kinet. 28, 103 (1996)) examined the oxidation of tris(1,10-phenanthroline) iron (II) by periodate in aqueous solution, a reaction which shows autocatalytic behaviour. To assess the kinetic salt effect, they measured rate constants at a variety of concentrations of Na SO, far in excess of reactant concentrations and reported the following data: Na SO4]/(molkg') 0.0125 0.005 0.2 0.15 0.025 0.1 0.05 k/(dm3/2 mol-1/2 s1) 0.462 0.430 0.252 0.224 0.390 0.321 0.283 What can be inferred about the charge of the activated complex of the rate- determining step? 89.6 For the gas-phase reaction A + A A2, the experimental rate constant, k has been fitted to the Arrhenius equation with the pre-exponential factor A=4.07x 105 dm3 mol-1s1 at 300 K and an activation energy of 65.43 kJ mol-1 Calculate A*S, A*H, A*U, and A*G for the reaction. 89.7 Use the Debye-Hückel limiting law to show that changes in ionic strength can affect the rate of reaction catalysed by H+ from the deprotonation of a weak acid. Consider the mechanism H+ + B- P, where H comes from the deprotonation of the weak acid, HA. The weak acid has a fixed concentration. First show that log [H+], derived from the ionization of HA, depends on the activity coefficients of ions and thus depends on the ionic strength. Then find the relationship between log(rate) and log [H] to show that the rate also depends on the ionic strength. f 89.8 Show that bimolecular reactions between nonlinear molecules are mvan when the activation energies of both

Physical chemistry quanta, matter and change Pronlblem 89.6 (Atkins, 2th)

Answer 1

Please ask all questions separately so that we can answer them in detail.

The solution of question 89.6 is as follows:
A A 4.09ID dm3 mof pre-erponertial factor) T- 3o0 K 5.43 kj mat 6.5430 Jm o1 AS AU7 4'H*= -RTInk AG AC TAS AH Ea AH RT Ea In kn = nA - RT 6543o n(4. &914 300 6.23 2.1 ky = exp k,= 1.64X10 &314 x 460) 65430 AH 62104.y I ma- 62.10 kJ mot es Scanned with CamScanner

: A G RT &-31MX 400 x (-13.32) Lmo kJ m AGT- 44296-99 4.30 AH AGT TAS+ AH-AG AS 762.J0 44.3D) X10 J mot AS J Kmo1^ 45 CS Seanned with CamScanner