38- The reaction A product is second order reaction , A solution originally at 0.6 M is found to be 0.075 M after 83 min, the half-life reaction is .... min: A) 11.85 B) 31 C) 83 D) 27.66 E) 47.43 Answer = A

11.48 The following data were collected for the decomposition of NT),-: Time, f (min) [N2Os] (mol L-1) 0 0.200 5 0.171 10 0.146 15 0.125 20 0.106 25 0.0909 30 0.0777 35 0.0664 40 0.0570 Use appropriate graphs to determine the rate constant for this reaction. Find the half-life of the reaction.

As with any drug, aspirin (acetylsalicylic acid) must remain in the bloodstream long enough to be effective. Assume that the removal of aspirin from the bloodstream into the urine is a lirst-order reaction, with a half-life of about 3 hours. The instructions on an aspirin bottle say to take 1 or 2 tablets every 4 hours. If a person takes 2 aspirin tablets, how much aspirin remains in the bloodstream when it is time for the second dose? (A standard tablet contains 325 mg of aspirin.)

The first-order rate constant for the decomposition of a certain hormone in water at 25C is 3.42104day1. (a) If a 0.0200 M solution of the hormone is stored at 25C for two months, what will its concentration be at the end of that period? (b) How long will it take for the concentration of the solution to drop from 0.0200 M to 0.00350 M? (c) What is the half-life of the hormone?