The half-lives of radioactive isotopes can be used to date objects. The half-life of a reaction is the time required for the reactant concentration to decrease to one-half its initial value. The half-life of a first-order reaction is a constant that is related to the rate constant for the reaction: t 1/2 = 0.693/ k.
The half-life of a drug is an estimate of the time it takes for the concentration or amount in the body of that drug to be reduced by exactly one-half (50%). The symbol for half-life is t½. For example, if 100mg of a drug with a half-life of 60 minutes is taken, the following is estimated: 2 1000 3 500 4 250 5 125 Half-Life Data-Teacher Answer Key 1.Hypothesize what halfâlifeis: Halfâlife is the amount of time it takes for approximately half of the radioactive atoms in a sample to decay intoa more stable form. Every radioactive element has a different halfâlife. 2.
âWe know the drug has a very short half life, which means it doesnât linger for long in the body,â says Ho. Ho is currently doing experiments in his lab to figure out how long the
Drugs with a long half-life tend to be detectable on standard urine drug tests for a longer period of time than drugs with a short half-life. The active ingredient in Valium, diazepam, has a half-life of around 48 hours while one of its metabolites (i.e. metabolism by-product), N-desmethyldiazepam, has a half life of nearly 100 hours.
Well it makes sense when we're talking about the 2nd order reaction, but what about the zeroth order one, where the half life would be t1/2=[A]°/2K, meaning that as the concentration increases, the half life will increase too, and also in the 1st order reaction, how can the half life be independent of the intial concentration t1/2=0.693/K ? Definition: Half-Life Model. If H H is the half-life of a quantity (the amount of time it takes the quantity be cut in half) and P0 P 0 is the initial amount of the quantity then the amount of the quantity present after t units of time is. P(t) = P0(1 2) t H P ( t) = P 0 ( 1 2) t H. Example 4.3.9 4.3. 9. 9pIh.
