CHEM 14B Lecture 9: Chem 14B Lecture 9 Notes

• School: UCLA
• Department: Chemistry and Biochemistry
• Course: CHEM 14B
• Professor: Lavelle Laurence

Document Summary

Reactions sometimes described by time taken for reactant concentration to decrease to half its original concentration, which is the half-life of the reaction (t 1/2 ) rate law). At t = t 1/2 , [a] = [a o ] t 1/2 = 0. 693 / k, is half-life of 1st order reaction. ln[a] = -kt + ln[a o ], equal to [a] = [a o ]e -kt called the decay constant. The half-life of a 1st order reaction: ln[a] = -kt + ln[a o ] (1st order integrated. Ln [a o ] = -kt 1/2 + ln[a o ] Plot of reactant vs time gives an exponential curve which is decreasing. Radioactive decay is a 1st order (nuclear) reaction. The rate constant k is number of radioactive atoms) e -kt rate law) Rdioactive decay = -dn/dt = kn (number of radioactive atoms) = kn o (initial. Second-order reaction: rate = -1/a d[a]/dt = k[a] 2 (2nd order differential.