  Home
Common Compounds
Exam Guide
FAQ
Features
Glossary
Construction Kits
Companion Notes
Simulations
Slide Index
Toolbox
Tutorial Index

FAQ
Introduction
Measurement
Matter
Atoms & ions
Compounds
Chemical change
The mole
Gases
Energy & change
The quantum theory
Electrons in atoms
The periodic table
Chemical bonds
Solids
Liquids
Solutions
Acids & bases
Redox reactions
 Reaction rates
Organic chemistry
Everyday chemistry
Inorganic chemistry
Environmental chemistry
Laboratory
History of chemistry
Miscellaneous Home FAQ Reaction rates Print | Comment
 Next Question

# How can I compute the half-life of a first order reaction?

I am confused about integrated rate reactions and half life problems. For example: The first order rate constant for the radioactive decay of radium-223 is 0.0606/day. what is the half life of radium-223?
Tara 02/05/99 Vocabulary half life first order reaction integrated rate law rate constant The rate law for this first order rate equation is where [A] is the concentration of radium-223 at time t and k is the rate constant (0.0606 day-1). You want to calculate the time it takes for the concentration to fall from [A]0 to ½[A]0. The rate law will have to be integrated.

Rearrange the equation so that all concentration dependent terms are collected on one side, and all time dependent terms are on the other: Integrating from time 0 to time t, the first order integrated rate equation is The half life is the time required for the concentration to drop to one-half its original value. We can write and solving for the half life, Author: Fred Senese senese@antoine.frostburg.edu

General Chemistry Online! How can I compute the half-life of a first order reaction?