rogerxd45 Posted December 9, 2011 Share Posted December 9, 2011 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 Link to comment Share on other sites More sharing options...
Horza2002 Posted December 10, 2011 Share Posted December 10, 2011 You've posted this in the wrong section. This is about organic chemistry not nuclear physics... Link to comment Share on other sites More sharing options...
mississippichem Posted December 10, 2011 Share Posted December 10, 2011 I imagine you can calculate this from half-life data and simple arithmetic. Link to comment Share on other sites More sharing options...
swansont Posted December 11, 2011 Share Posted December 11, 2011 Half lives can be looked up here http://atom.kaeri.re.kr/ton/ [math]A=\lambda N[/math] where [math]\lambda = \frac{0.692}{t_\frac{1}{2}}[/math] N is the number of atoms, so you need to do some molar calculations Link to comment Share on other sites More sharing options...
John Cuthber Posted December 11, 2011 Share Posted December 11, 2011 You've posted this in the wrong section. This is about organic chemistry not nuclear physics... I think you are half right. Link to comment Share on other sites More sharing options...
rogerxd45 Posted December 11, 2011 Author Share Posted December 11, 2011 (edited) Half lives can be looked up here http://atom.kaeri.re.kr/ton/ [math]A=\lambda N[/math] where [math]\lambda = \frac{0.692}{t_\frac{1}{2}}[/math] N is the number of atoms, so you need to do some molar calculations so is [math]{t_\frac{1}{2}}[/math] the half life? Edited December 11, 2011 by rogerxd45 Link to comment Share on other sites More sharing options...
John Cuthber Posted December 11, 2011 Share Posted December 11, 2011 Yes. Link to comment Share on other sites More sharing options...
rogerxd45 Posted December 11, 2011 Author Share Posted December 11, 2011 (edited) 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 December 11, 2011 by rogerxd45 Link to comment Share on other sites More sharing options...
John Cuthber Posted December 11, 2011 Share Posted December 11, 2011 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. Link to comment Share on other sites More sharing options...
rogerxd45 Posted December 11, 2011 Author Share Posted December 11, 2011 (edited) 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 ------------------------------------------------------------------------ so i did some googling of the equation you posted [math]\lambda = \frac{0.692}{t_\frac{1}{2}}[/math] and Lambda are you sure 0.692 is correct? everything else says [math]\lambda = \frac{0.693}{t_\frac{1}{2}}[/math] instead of [math]\lambda = \frac{0.692}{t_\frac{1}{2}}[/math] ---------------------------------------------------------------------------- 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 December 11, 2011 by rogerxd45 Link to comment Share on other sites More sharing options...
John Cuthber Posted December 11, 2011 Share Posted December 11, 2011 "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. Link to comment Share on other sites More sharing options...
rogerxd45 Posted December 11, 2011 Author Share Posted December 11, 2011 (edited) "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 December 11, 2011 by rogerxd45 Link to comment Share on other sites More sharing options...
swansont Posted December 12, 2011 Share Posted December 12, 2011 so i did some googling of the equation you posted [math]\lambda = \frac{0.692}{t_\frac{1}{2}}[/math] and Lambda are you sure 0.692 is correct? everything else says [math]\lambda = \frac{0.693}{t_\frac{1}{2}}[/math] instead of [math]\lambda = \frac{0.692}{t_\frac{1}{2}}[/math] Typo, sorry. It's almost as if those are adjacent on the keyboard or something ln(2) = 0.693 is correct Link to comment Share on other sites More sharing options...
rogerxd45 Posted December 12, 2011 Author Share Posted December 12, 2011 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 Link to comment Share on other sites More sharing options...
swansont Posted December 12, 2011 Share Posted December 12, 2011 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. Link to comment Share on other sites More sharing options...
rogerxd45 Posted December 13, 2011 Author Share Posted December 13, 2011 (edited) 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 December 13, 2011 by rogerxd45 Link to comment Share on other sites More sharing options...
swansont Posted December 13, 2011 Share Posted December 13, 2011 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. Link to comment Share on other sites More sharing options...
rogerxd45 Posted December 14, 2011 Author Share Posted December 14, 2011 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? Link to comment Share on other sites More sharing options...
swansont Posted December 14, 2011 Share Posted December 14, 2011 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. Link to comment Share on other sites More sharing options...
rogerxd45 Posted December 14, 2011 Author Share Posted December 14, 2011 is the "branch ratio" the other mode of decay? in the link you posted about half lives it says 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 Link to comment Share on other sites More sharing options...
rogerxd45 Posted December 17, 2011 Author Share Posted December 17, 2011 anyone? Link to comment Share on other sites More sharing options...
John Cuthber Posted December 17, 2011 Share Posted December 17, 2011 is the "branch ratio" the other mode of decay? in the link you posted about half lives it says 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. Link to comment Share on other sites More sharing options...
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