Thus, for a first-order reaction, each successive half-life is the same length of time, as shown in Figure 1, and is independent of [A]….Half-Lives and Radioactive Decay Kinetics.
Q. What percent of the parent is left after 5 half lives?
What percentage of the isotope would remain as parent material? If D=96.875%, then 5 half lives have passed.
Table of Contents
- Q. What percent of the parent is left after 5 half lives?
- Q. Why do radioisotopes differ in the length of their half lives?
- Q. How do you know if something is zero first or second order?
- Q. How do you know if its first or second order?
- Q. When initial concentration of the reactant is doubled?
- Q. Why is elimination of a drug zero order?
Q. Why do radioisotopes differ in the length of their half lives?
Variation in Half-Lives Different radioisotopes may vary greatly in their rate of decay. That’s because they vary in how unstable their nuclei are. The more unstable the nuclei, the faster they break down. One half-life is 5,700 years, so two half-lives are 11,400 years.
| Number of Half-Lives | Percentage of Reactant Remaining | |
|---|---|---|
| 2 | 50%2=25% | 12(12)(100%)=25% |
| 3 | 25%2=12.5% | 12(12)(12)(100%)=12.5% |
| n | 100%2n | (12)n(100%)=(12)n% |
Q. How do you know if something is zero first or second order?
If an increase in reactant increases the half life, the reaction has zero-order kinetics. If it has no effect, it has first-order kinetics. If the increase in reactant decreases the half life, the reaction has second-order kinetics.
Q. How do you know if its first or second order?
The overall order of the reaction is found by adding up the individual orders. For example, if the reaction is first order with respect to both A and B (a = 1 and b = 1), the overall order is 2. We call this an overall second order reaction.
Q. When initial concentration of the reactant is doubled?
when initial concentration of the reactant is doubled, the half-life period of a zero order reaction. Step by step solution by experts to help you in doubt clearance & scoring excellent marks in exams. remains unchanged. Thus, if [A]0 is doubled, t1/2 also becomes double.
Q. Why is elimination of a drug zero order?
Zero order elimination kinetics: a constant amount (eg. so many milligrams) of drug is eliminated per unit time. First order kinetics is a concentration-dependent process (i.e. the higher the concentration, the faster the clearance), whereas zero order elimination rate is independent of concentration.
