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It's a process involving experimentation and mathematical modelling.
Method #1:
One way to solve for half-life is to use the following equation:
t1/2 = (t ln 1/2)/(ln mf/mi)
where:
t1/2 = half-life
t = time that has passed
mf = the final or remaining mass of undecayed sample
mi = the initial or original mass of undecayed sample
(The fraction mf / mi is of course equivalent to the fraction or percentage of undecayed sample remaining, in case you are given the fraction remaining rather than specific masses.)
Note: You can also use base-10 logarithms instead of natural logarithms.
For instance, you are told that after 2.00 hours a sample decays such that 80.0% remains undecayed. Substituting these values into the formula allows us to find the half-life of the substance in essentially one step:
t1/2 = (2.00*ln(0.5))/(ln(0.800)) = 6.21 hours
Method #2:
Half-life can alternatively be found in a two-step process using the related model:
At = A0e-Bt
where:
At = Amount at time t
A0 = Initial amount
e = exponential
B = a constant
t = time
However, before you can determine a half-life, first you need to determine what the constant, B, is. This can be done via experimentation. For example, imagine you are observing the decay of a radioactive substance. After 2.00 hours you determine that you only have 80.0% left of the initial amount...
That is, A2 = 0.800A0
So, 0.800A0 = A0e-2.00B
Rearrange to get B = -ln(0.800)/2.00 = 0.1116
So now you have what you need to determine the half life. That is, how many hours will it take before you only have 50.0% left of the decaying substance?
As above, 0.500A0 = A0e-Bt
Solving for t this time, t = -ln(0.5)/B = -ln(0.5)/0.1116 = 6.21 hours.
Note: As in the other method, you could also have used base-10 logarithms instead of base-e (natural) logarithms. Just be sure to use the same base in all your calculations.
As you can see, both these methods yield the same answer, a half-life for the substance of 6.21 hours.
Wiki User
∙ 12y ago
Wiki User
∙ 9y agoIn order to find the Half-life, it is equal to the amount of time it takes for half of the atoms to decay.
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How do you determine the half life of a radioactive substance that has changed through radioactive decay After 40 days the original substance left is is one sixteenth of the original amount?
the halflife is 10 days
Does uranium 238 have the shortest half life?
The half life of 238U is 4,468.109 years; this is a very long halflife !
What are ways you can turn uranium into energy that we can use?
Most uranium is U-238, with has a very long halflife. Bombard it with neutrons (fast breeder reactor) to make plutonium-239, which is a suitable fuel for a fission reactor. Lift it up high, and tie a rope to it. As it falls, have it drive a generator. Same scenario, only drop it into a black hole... get lots more energy.
After a nuclear bomb is droped how long does the after affects stay for?
That varies, but as most radioisotopes produced in a typical nuclear blast are short halflife, the area is likely to be safe to reoccupy in a few weeks to months. It gets more complex to predict with many blasts (especially high fallout surface bursts). Radiological surveys should be taken first to identify any radioactive hotspots so they can be marked off as hazard zones.
As temperature increase pressure remaining constant the half life of a radioactive element?
In general, and at temperatures one might commonly find on Earth, temperature has no appreciable effect on half life. If the temperature of an atom is elevated sufficiently, we can get effects in which the question of half life becomes moot, because the atom is no longer able to hold together in atomic form, but I am supposing that is not what this question is about.There are certain circumstances, under which the half life might be affected by temperatures that a person might consider more ordinary. One such place is in a neutron rich environment, such as in the core of a nuclear reactor. Neutrons colliding with the nuclei of atoms can cause the atom to become a different isotope of the same element, to decay, or to undergo fission. The probability of the neutron colliding with the nucleus depends on what is called the "nuclear cross section" which is measured in a unit called a "barn." The nuclear cross section generally increases with temperature, though as the temperature increases, the actual value goes up and down, depending on the temperature and the specific isotope involved.So, in a neutron rich environment, increasing the temperature generally reduces the half life.
When was Illadelph Halflife created?
Illadelph Halflife was created on 1996-09-24.
To find the halflife period of curium?
For the half lives of all curium isotopes see the link below.
Will Valve be releasing a HalfLife 4?
Yes.
Can you use halflife to determine when dinosaurs died?
yes
What is the correct order of nuclear decay mode for the changes from U-238 to U-234?
U-238 --> alpha + gamma + Th-234, halflife 4.51E9 yearsTh-234 --> beta- + gamma + Pa-234, halflife 24.10 daysPa-234 --> beta- + gamma + U-234, halflife 6.66 hours
Is lambda the halflife logo?
The logo has a border, however the lambda is in the center.
Is lithium 8 an isotope why?
Yes, but it has a halflife of only 0.86 seconds.
What is the halflife of Carbon-11?
The half-life of carbon-11 is 20.334 minutes.
Where can I download halflife that works on my removable drive?
Go out and buy it. You can't download it.
What is the halflife of Uranium-239?
The half-life of uranium-239 is 23.45 minutes.
What is the halflife of plutonium 235?
The half life of plutonium-235 is 25,3(5) minutes.
Can you use carbon dating to find out how old something is around 40 years old or newer?
Carbon dating measures the amount of carbon halflives that an object's carbon-14 has seen. A halflife is the amount of time it takes for half of the C-14 present to decay into a different element (N-14). A carbon halflife is 5730 years so you wouldn't be able to tell with such a small amount of time.
