# strongest alpha emitter

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which of the following is the strongest alpha emitter by strongest i mean produces the most alpha particles

-Americium from smoke detector

-0.25 gram of thorium dioxide ((very fine powder)

-2 grams thorium nitrate

-2 grams uranium nitrate

-radium from alarm clock, weight unknown but the clock face is about 5" and he numbers are fairly large

-5 grams of U238 (5g is the total weight of several chunks of the metal)

-several ounces of uranium glass (im pretty sure this one isnt the winner)

-last and definitely least.... several pounds of Bismuth

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You've posted this in the wrong section. This is about organic chemistry not nuclear physics...

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I imagine you can calculate this from half-life data and simple arithmetic.

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Half lives can be looked up here http://atom.kaeri.re.kr/ton/

$A=\lambda N$

where $\lambda = \frac{0.692}{t_\frac{1}{2}}$

N is the number of atoms, so you need to do some molar calculations

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You've posted this in the wrong section. This is about organic chemistry not nuclear physics...

I think you are half right.

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Half lives can be looked up here http://atom.kaeri.re.kr/ton/

$A=\lambda N$

where $\lambda = \frac{0.692}{t_\frac{1}{2}}$

N is the number of atoms, so you need to do some molar calculations

so is ${t_\frac{1}{2}}$ the half life?

Edited by rogerxd45

Yes.

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so for the thorium compounds do i need to figure out the thorium content by % and multiply that by the weight of the compound?

example

thorium dioxide the thorium content is 89.8809% of the molecular weight of ThO2

so i have .25 gramsx0.898809

which gives me 0.22470225 grams of thorium

Th has 232.038g/M so would

so is 0.00096838556157267344141907790962527 moles of Th be correct?

if it is correct do i multiply that number by 6.022*10^23? to give me total number of atoms?

BTW this is not for homework, i just enjoy this type of stuff

Edited by rogerxd45
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Yes, that looks right. But I have to ask, have you ever heard of "spurious accuracy"?

You have specified the number of moles to so many places of decimals that you seem to be counting about a millionth of a single atom.

If your thorium oxide is 99.99% pure (which would be quite a high quality sample, then anything more than 5 digits is meaningless.

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Yes, that looks right. But I have to ask, have you ever heard of "spurious accuracy"?

You have specified the number of moles to so many places of decimals that you seem to be counting about a millionth of a single atom.

If your thorium oxide is 99.99% pure (which would be quite a high quality sample, then anything more than 5 digits is meaningless.

yes i have, i was just putting the exact numbers i came up with just to see if my math was correct

my thorium dioxide is 99.9995% pure, it is a VERY pure sample

and i weighed my thorium nitrate its actually 5.041g and the uranium nitrate is 3.871g

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so i did some googling of the equation you posted $\lambda = \frac{0.692}{t_\frac{1}{2}}$ and Lambda

are you sure 0.692 is correct? everything else says $\lambda = \frac{0.693}{t_\frac{1}{2}}$ instead of $\lambda = \frac{0.692}{t_\frac{1}{2}}$

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using the 0.693 figure i came up with

A=287637807147.583723

my question is what exactly is A? i assume its number of alpha particles emitted since thats what my question was. but whats the time frame? is that number of alpha partials emitted for the halflife of thorium or some other time frame?

Edited by rogerxd45
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"my thorium dioxide is 99.9995% pure, it is a VERY pure sample"

I'm willing to bet that it isn't.

They usually quote analyses like that on a "metals" basis.

There's likely to be more than 5 ppm of water in it.

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"my thorium dioxide is 99.9995% pure, it is a VERY pure sample"

I'm willing to bet that it isn't.

They usually quote analyses like that on a "metals" basis.

There's likely to be more than 5 ppm of water in it.

yes this thorium dioxide is 99.9995% pure on a metals basis, i thought that was pretty much a given

water is very easy to drive off when the melting point of said oxide is 3300 C

that is still a VERY pure sample

do you have an answer to my other questions through?

Edited by rogerxd45
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so i did some googling of the equation you posted $\lambda = \frac{0.692}{t_\frac{1}{2}}$ and Lambda

are you sure 0.692 is correct? everything else says $\lambda = \frac{0.693}{t_\frac{1}{2}}$ instead of $\lambda = \frac{0.692}{t_\frac{1}{2}}$

Typo, sorry. It's almost as if those are adjacent on the keyboard or something

ln(2) = 0.693 is correct

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Typo, sorry. It's almost as if those are adjacent on the keyboard or something

ln(2) = 0.693 is correct

and is my answer total number of alpha particles? if so whats the time frame

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and is my answer total number of alpha particles? if so whats the time frame

The activity (A) will be number of decays per unit time of whatever you use for the half-life.

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by unit of time do you mean the total half life or the unit i use to descibe the half life

so is it 1 year

or

14.05 billion years <half life of thorium

Edited by rogerxd45
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by unit of time do you mean the total half life or the unit i use to descibe the half life

so is it 1 year

or

14.05 billion years <half life of thorium

If you put the half-life in years, the activity will be the number of decays per year. If you use seconds, it will be decays per second.

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thank you for all your help

one last question if an element decays by alpha and bete like 70% alpha 30% beta, do i take 70% of the number of decays to figure total alpha paricles?

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one last question if an element decays by alpha and bete like 70% alpha 30% beta, do i take 70% of the number of decays to figure total alpha paricles?

Yes, if what you are given is the overall half-life.

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is the "branch ratio" the other mode of decay?

Half life: 1.405E10 years

Mode of decay: Alpha to Ra-228

Decay energy: 4.083 MeV

Mode of decay: SF

Branch ratio: <1.0E-9 %

so all but 1.0E9 percent is alpha radiation and <1.0E-9 % is spontaneous fission

anyone?

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is the "branch ratio" the other mode of decay?

Half life: 1.405E10 years

Mode of decay: Alpha to Ra-228

Decay energy: 4.083 MeV

Mode of decay: SF

Branch ratio: <1.0E-9 %

so all but 1.0E9 percent is alpha radiation and <1.0E-9 % is spontaneous fission

Yes.

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