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Textbook question 7.23

Posted: Thu Mar 12, 2020 10:17 am
by Paige Lee 1A
For part C, could someone please explain why, as pH increases, [OH-] increases, so the reaction rate decreases?

a) What is the overall reaction for the following mechanism?
ClO2 1 H2O ∆ HClO 1 OH2 HClO 1 I2 ¡ HIO 1 Cl2 HIO 1 OH2 ∆ IO2 1 H2O
(fast equilibrium) (very slow)
(fast equilibrium)
(b) Write the rate law based on this mechanism. (c) How will the reaction rate depend on the pH of the solution? (d) How would the rate law differ if the reactions were carried out in an organic solvent?

Re: Textbook question 7.23

Posted: Thu Mar 12, 2020 11:00 am
by Tanmay Singhal 1H
ph is concentration of H+ and if it increases then OH- increases because it is becoming more basic

Re: Textbook question 7.23

Posted: Thu Mar 12, 2020 11:13 am
by jisulee1C
Increasing the pH would mean that the solution is becoming more basic with more OH- ions. And because the OH- ions are products of the first step of the mechanism (the fast equilibrium step), increasing the pH, increases OH-, which increases the amount of products favoring the reverse reaction therefore more reactants will form in the fast equilibrium. Since the product HClO from the fast equilibrium is a reactant for the very slow step, having less of the HClO from the previous reaction would mean less reactants for the slow rate determining step and the rate would decrease.