The time taken for half of the original population of radioactive atoms to decay is called the half-life. This relationship between half-life, the time period, t
1 / 2
, and the decay constant λ is given by
t12=0.693λ t 1 2 = 0.693 λ
.
How do you calculate the half life of strontium-90?
For example, the half-life of strontium-90 is
28.8 years
. If you start with 10 grams of
90
Sr and wait 28.8 years, you'll have 5 grams left of
90
Sr. If another 28.8 years go by, 2.5 grams will remain.
What is the half-life of strontium-90 math?
Strontium 90 is a radioactive element with a half-life of
28 years
.
How would you determine the half-life of this unknown element?
So, if a problem asks you to calculate an element's half-life, it
must provide information about the initial mass, the quantity left after radioactive decay, and the time it took that sample to reach its post-
decay value. Therefore, its half-life is t1/2=98.012.7=7.72 years .
In what year will only 0.625 grams of the strontium-90 remain?
Answer and Explanation: From 1960, it will take 56 years to reduce 2.5 g of strontium-90 to 0.625 g. Thus, it will be in
2016
.
How long does it take for 80% of a strontium-90 sample to decay if it has a half-life of 29 years?
And only half of that radiation will be gone in 29 years. It will take
291 years
for the strontium 90 to decay to the same radioactivity that the iodine 131 has after 80 days.
What is the value of the rate constant for the decay of strontium-90?
Therefore, the equation for the amount…
What is the number of half-life periods required for a sample of a radioactive material?
Half-life (
t1/2
) is the time required for one half of the nuclei in a sample of radioactive material to decay. After each half-life has passed, one half of the radioactive nuclei will have transformed into a new nuclide (see table below).
Which is the correct equation for the decay of polonium 210?
Polonium-210, 210Po, decays to lead-206, 206Pb, by alpha emission according to the equation
84Po210 → 82Pb206 + 2He4
If the half-life, t1/2, of 210Po is 138.4 days, calculate the mass of 206Pb produced from a 574.0 mg sample of Polonium(IV) chloride, PoCl4, that is left untouched for 333.5 days.
How long does it take to decay to 12.5% of the initial amount of strontium-90?
Since the half-life of strontium-90 is 28 years, this means that half of our strontium-90 will decay in 28 years. After
84 years
, our sample will contain 12.5 grams of strontium-90.
What is the rate constant for the first order decay of strontium-90?
For example, if we wanted to find the rate constant for the radioactive decay of Strontium-90, the rate constant would be equal to
0.693 divided by the half-life of Strontium-90
, which we saw was 28.8 years.
What is the half-life for carbon 14?
Carbon-14 has a half-life of
5,730 ± 40 years
—i.e., half the amount of the radioisotope present at any given time will undergo spontaneous disintegration during the succeeding 5,730 years.
How long will it take the sample to decay to 20% of its original amount?
Answer: If t1 is the time it takes the sample to decay to 20% of its original amount, 0.2 = N(t1) = (0.945)t1 , 1 Page 2 meaning that (if we take the natural log of both sides), ln(0.2) = ln(0.945t1 ) = t1 ln(0.945), so t1 = ln(0.2) ln(0.945) ≈
28.45 years
.
What is the reason for the decay of naturally radioactive elements?
Every atom seeks to be as stable as possible. In the case of radioactive decay, instability occurs
when there is an imbalance in the number of protons and neutrons in the atomic nucleus
. Basically, there is too much energy inside the nucleus to hold all the nucleons together.
How long does it take a 100.00 g sample of AU 198 to decay to 6.25 g?
100 g of Au-198 would have a half life of
2.7 days
.
What happens when polonium 210 undergoes alpha decay?
alpha decay
Thus polonium-210 (mass number 210 and atomic number 84, i.e., a nucleus with 84 protons) decays by alpha emission to
lead-206 (atomic number 82)
.
Does the atomic number change when polonium 211 decays?
Polonium-211 is a very unstable isotope of polonium that will undergo alpha decay very quickly. The mass is reduced by 4 from 211 to 207, and the atomic number is reduced by 2 from 84 to 82. The atom is therefore
changed from polonium to lead
.
When 238 92 U becomes 234 90 th what type of decay has taken place?
Uranium-238 undergoes
alpha decay
to become thorium-234. (The numbers following the chemical names refer to the number of protons plus neutrons.)
How do you write a gamma decay equation?
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What is a half-life in chemistry?
half-life, in radioactivity,
the interval of time required for one-half of the atomic nuclei of a radioactive sample to decay
(change spontaneously into other nuclear species by emitting particles and energy), or, equivalently, the time interval required for the number of disintegrations per second of a radioactive …
How do you calculate alpha particle emitted?
So first look at the father nucleus and list its number of protons and its atomic weight. Step 3) Now from
number of neutrons subtract 2
and from number of protons subtract 2 as an alpha particle has 2 neutrons and 2 protons and in an alpha decay an alpha particle will always form in case of any any father nucleus.
How long will it take to get 25 percent of strontium-90?
It takes 28.8 years for half of the strontium to decay to 50 grams. This is called one half-life. After 28.8 more years, strontium-90 has decayed to 25 grams. This is called
two half-lives
.
How much of a parent isotope is left in a sample after 2 half-lives?
The ratio of parent to daughter after one half-life will be 1:1. After two half-lives, half of the remaining half will decay, leaving
one-quarter of
the original radioactive parent atoms.
How much of the sample is remaining after the third half-life?
After three half-lives
1/8
(12.5%) of the original sample remains. A half-life is the amount of time it takes for one half of a sample to undergo…
How is actual yield calculated?
The formula to determine actual yield is simple:
you multiply the percentage and theoretical yield together.
How do I calculate theoretical yield?
Multiply the ratio by the limiting reactant's quantity in moles
. The answer is the theoretical yield, in moles, of the desired product.
How do you calculate half-life?
The
time taken for half of the original population of radioactive atoms to decay
is called the half-life. This relationship between half-life, the time period, t
1 / 2
, and the decay constant λ is given by t12=0.693λ t 1 2 = 0.693 λ .
How many days is a half-life?
You know that the half-life of a radioactive nuclide, t1/2 , tells you the time needed for half of the atoms present in a sample to undergo radioactive decay. In this case, it takes
3.6 days
for any sample of this substance to decay to half of its initial mass.
