Question

6. Autocatalysis occurs when a reaction product can act as a catalyst for the overall reaction. Clearly, this can accelerate the reaction rate, and can lead to fascinating phenomena, such as oscillating reactiosn. Which of the following elementary reactions could make an overall reaction autocatalytic? Explain why. (a) A+B-, C + D (b) A B A+B (c) A+B A+D (d) A+B A +A

Answer 1

Solutian. Note1- Please 2o thrtough till end hene is the Praper 4Yx se through f Reacton Explaiuto of Autocuhaly the reaution Wis treaeten could make an ovenall neachian autocatnlytic A reachion in luch one of the Products of reachon Explainastion ls as a calelyst is callad onleeadten fore which the tste ez" solcs Beceuse the total numbet of moles of A & B Temains uncharpe! as 8 is cansumed, twe may wnite that at any tine CB & CA > Final concentratons C8。3cA。→ Initial concentrations Thus, the tcate eguaton becemes dit raa breaki ial rachon, use elbtain lilkih on indegnuton gives In terms of the initial rear ant ratto M=-CA. 8 ftachoral conuensi., of 8, this can be uuniten as

M (1-XA) Cenvexsion time cuhve fore Aub catuliytic Treachion low rute Hgh raje louo rtate 피 Kate-Concenhtuhon curve fort autocatalyh'crtearhon Proess in t Start with Some A Present Parabolic Fort an autocatalyHc teaution ina batdh reactot Some prodact A' must be present it the Treaction is to Pmacceol atull startin午with avere, small concentration of A, we see qualitatively that the teate ui]I rise as A' ts forme d. vAt the otker extreme, twhen is just about used up the trate muyt drap to zexo. Ths result is iven in abeve mexthoned fiure, wwch shawes that the rate folleuis a parabola, uith Showes Ihat naximum ushere tu cancertrations of Bfre equa the Th on autocafalytiL rteae, howeve, the hate Sant is louw because little Product is present, it increases to a maximum as Produt is fotmed and then drapes oujan to a louw value. as πeachant's consumed.