CHEM105 Lecture Notes - Lecture 3: Reaction Rate Constant, Rate Equation, Reaction Rate

• School: University of Alberta
• Department: Chemistry
• Course: CHEM105
• Professor: Sai Yiu

Document Summary

The half-life of a from the above graph is 7 seconds. We could pick any initial concentration and find that the half-life is still 7 seconds. Hence we may say that for first order reactions, the half-life is independent on initial concentrations. When [a] = [a]0 t = t . [a]o = [a]o e kt 1/2 e kt = k t = ln 2 = 0. 693 ln 2. Hence from the half-life of a first order reaction, we can find the rate constant, k. Thus, the rate constant for the above reaction is: Therefore, k = = 0. 1 / s (0. 099 s-1) Graph of 1 / [a] vs time for a second order reaction gives a straight line with the slope = k (fig 16. 10b p694) Half-life (t 1/2) = ______ k [a]o t 1/2 = k [a]o. Plot of reactant concentration [a] against time for different order of reactions.