Question

15. At 25°C, k = 1.55 dm mol 2 min' at an ionic strength of 0.0241 for a reaction in which the rate-determining step involves the encounter of two singly charged cations. Use the Debye-Hückel limiting law to estimate the rate constant at zero ionic strength.

Answer 1

Lonic strength of the aduto com considerably affect the ratese reaction, this is known as primasy Kinetic salt efect. For this if the rate constant of a reaction in Koot zero Torric strength. and trate content kat fame strength i then, logk= log ko + 2A 2AZBI ZA Charge of a & ZBt Charge of B for the reaction, h2h + B²B [XH7A1B), A Debye Huckel constant. A=0.52 for Water at 25°c. loy k = log ko + 2AZA ZB FT Here the reactants are two singly charged cation I :.ZA=1 ZB=1 and iconic strength i=0.0241 loy ko = logk - ZAZAZBJE - 101.55 - 2x0.52% 1X LX V0.0241- = 0.1903 - 0.1614 & lozko = 0.0288 only toots-color are 1 ko = 1.068 dno mot 2 mint

9# AaB derivation AZA + 8 2 4 x #7323) k pats er = k'[*# equiin cont k = A activity of a = [X] # [AB] Vado ::8=k' k# [AJIB dan i activity coefficient k = k'k for the second orderrean r=K[AB] 8 [B3 YA EM CAD & K = Ko dare taking looge, From debye Huckel kimitinglan, logk= tog ko + loyda + logo logo log i=-AZ VI logk = loyko 4-A [ZA2 +70 - (ZA+Z3) ²] II It iomic strength look = log ko +2AZA ZB VIND At Deby Auckel comtemt - proofred) : k- 1 - 6 [5][6] %#