﻿ Half life formula

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7/17/2014
02:33 | Author: Kayla Henderson How to Calculate Half Life (with Calculator) - wikiHow

The half-life of a substance undergoing decay is the time it takes for the amount The formula for calculating half life is as follows: t1/2 = t * ln(2)/ln(N0/Nt); In this.

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The half-life of a substance undergoing decay is the time it takes for the amount of the substance to decrease by half. It was originally used to describe the decay of radioactive elements like uranium or plutonium, but it can be used for any substance which undergoes decay along a set, or exponential, rate. You can calculate the half-life of any substance, given the rate of decay, which is the initial quantity of the substance and the quantity remaining after a measured period of time.

Comments (1)Read more ## HALF-LIFE CALCULATOR

5/16/2014
12:26 | Author: Emma Coleman HALF-LIFE CALCULATOR

Half-Life Calculator, exponential decay, Radioactivity. The above formulas are used in calculations involving the exponential decay of radioactive materials.

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## Half-lives - Chemwiki

3/15/2014
02:39 | Author: Brandon Powell Half-lives - Chemwiki

In order to find the half life we need to isolate t on its own, and divide it by 2. We would end up with a formula as such depict how long it takes.

Half-life: the amount of time it required for a reaction to undergoing decay by half.

Determine its rate constant k?

4. In first order half life, what is the best way to determine the rate constant k? Why?

How much time required for this reaction to be at least 50% and 60% complete?

As in zero and first order reactions, we need to isolate T on its own:

Half-life of second order reactions shows concentration vs. time (t), which is similar to first order plots in that their slopes decrease to zero with time.

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## Half Life Calculator - MiniWebtool

11/24/2014
06:28 | Author: Emma Coleman Half Life Calculator - MiniWebtool

About This Tool. The online Half Life Calculator is used to calculate the half-life in exponential decay. Half-life Calculation Formula in Exponential Decay.

The online Half Life Calculator is used to calculate the half-life in exponential decay. Definition Half-life is the period of time it takes for a substance undergoing decay to decrease by half. It is usually used to describe quantities undergoing exponential decay (for example radioactive decay) where the half-life is constant over the whole life of the decay, and is a characteristic unit (a natural unit of scale) for the exponential decay equation. However, a half-life can also be defined for non-exponential decay processes, although in these cases the half-life varies throughout the decay process. The calculation of half-life used in this tool is based on the exponential decay equation. Half-life Calculation Formula in Exponential Decay An exponential decay process can be described by the following formula: where: N(t) = the quantity that still remains and has not yet decayed after a time t N 0 = the initial quantity of the substance that will decay t 1/2 = the half-life of the decaying quantity.

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## Some useful equations for half-lives Nuffield Foundation

9/23/2014
04:25 | Author: Kayla Henderson Some useful equations for half-lives Nuffield Foundation

The solution of this equation is an exponential one where N0 is the initial After one half life, the number, N of particles drops to half of N0 (the starting value).

The rate of decay of a radioactive source is proportional to the number of radioactive atoms (N) which are present. is the decay constant, which is the chance that an atom will decay in unit time. It is constant for a given isotope. The solution of this equation is an exponential one where N 0 is the initial number of atoms present. Constant ratio This equation shows one of the properties of an exponential curve: the constant ratio property. The ratio of the value, N 1, at a time t 1 to the value, N 2, at a time t 2 is given by: In a fixed time interval, t 2 – t 1 is a constant. Therefore the ratio So, in a fixed time interval, the value will drop by a constant ratio, wherever that time interval is measured. Straight line log graph Another test for exponential decay is to plot a log graph, which should be a straight line. Since Taking natural logs of both sides: Therefore a graph of N against t will be a straight line with a slope of -λ. Half-life and decay constant The half-life is related to the decay constant. A higher probability of decaying (bigger λ) will lead to a shorter half-life. This can be shown mathematically. After one half life, the number, N of particles drops to half of N 0 (the starting value). So: By substituting this expression in equation (1) above.

Taking natural logs of both sides gives:

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