EvoN1020v Posted October 28, 2005 Share Posted October 28, 2005 You are a physician in an emergency ward. A girl has entered respiratory collapse due to chewing on wood covered with a lead-based paint. Tests have shown [ce]PB^2+[/ce] in her blood to be 1.5 x 10^-5 mol/L. Reports have shown that [Pb] > 1.0 x 10^-9 can be considered lethal. To quickly reduce [Pb] to 1.0 x 10^-9 mol/L you have decided to inject a [ce]Na2CO3[/ce] solution directly into her blood so as to cause a [ce]PBCO3[/ce] precipitate to form [ce]K_sp = 3.3 x 10^-14)[/ce], which can be filtered from the blood by her kidneys. If her body contains 1.7L of blood, what mass of [ce]Na2CO3[/ce] is required to precipitate the Pb from her blood and bring [Pb^2+] down to 1.0 x 10^-9 mol/L. Since [ce]Na2CO3[/ce] is lethal in large amounts you must not administer an overdose!! So figure it yourself, and post your answer. I'll figure it out myself first, then we can discuss more later. Link to comment Share on other sites More sharing options...
jdurg Posted October 28, 2005 Share Posted October 28, 2005 Heh. So we'll ignore the fact that the precipitate would wind up blocking the arteries and veins in her brain and vital organs and kill her instantly? Link to comment Share on other sites More sharing options...
EvoN1020v Posted October 29, 2005 Author Share Posted October 29, 2005 You misunderstood for 3 reasons: (1)The solution is being injected - meaning the solution is in a needle and being put in the arm or something like that. (2)The precipitate will form inside her body, not in the mouth!! (3)It won't be too much precipitate enough to kill her. So jdurg the Chemistry Expert.. Do you have an answer for my question yet?? Link to comment Share on other sites More sharing options...
Jarryd Posted October 29, 2005 Share Posted October 29, 2005 Ok this is likely to be wrong but i got 0.0027 grams of PbCO3, although i have a feeling that may kill her lol Link to comment Share on other sites More sharing options...
builgate Posted October 29, 2005 Share Posted October 29, 2005 [Pb2+] = 1.5 x 10-5 mol dm-3 [Pb2+] > 1.0 x 10-9 is lethal Ksp of PbCO3 = 3.3 x 10-14 Volume of blood = 1.7 dm3 ~~~~~~~~~~PbCO3~~~~>> ~~~~~Pb2+ ~~~~+~~~CO32- Initial~~~~~~1.5 x 10~~~~~~~~~~~~y~~~~~~~~~~~ - Changes~~–(1.4999 x 10-5 )~~~–(1.4999 x 10-5 )~~~+(1.4999 x 10-5 ) Equilibrium~~~1.0 x 10-9~~~~ y –(1.4999 x 10-5 ) Ksp = [Pb2+][ CO32-] (1.0 x 10-9 ) (y –1.4999 x 10-5 ) = 3.3 x 10-14 y = 4.7999 x 10-5 no of mole of Na2CO3 = 4.7999 x 10-5 volume of blood Mass of Na2CO3 /106 = 4.7999 x 10-5 1.7 Mass = 8.65 x 10-3 g Is this correct ? Link to comment Share on other sites More sharing options...
builgate Posted October 29, 2005 Share Posted October 29, 2005 I am wondering how kidney is able to filter out the precipitate? Link to comment Share on other sites More sharing options...
insane_alien Posted October 29, 2005 Share Posted October 29, 2005 Heh. So we'll ignore the fact that the precipitate would wind up blocking the arteries and veins in her brain and vital organs and kill her instantly? - Jdurg You misunderstood for 3 reasons:(1)The solution is being injected - meaning the solution is in a needle and being put in the arm or something like that. (2)The precipitate will form inside her body, not in the mouth!! (3)It won't be too much precipitate enough to kill her. -Evo 1. Jdurg probably knew that(if he didn't i'll eat my hat) 2. where the hell did Jdurg say it formed in her mouth. the precipitate would form in the arteries and veins which would then cause blockages and strokes in the brain. 3. it probably would be. Link to comment Share on other sites More sharing options...
EvoN1020v Posted October 29, 2005 Author Share Posted October 29, 2005 Ok this is likely to be wrong but i got 0.0027 grams of PbCO3, although i have a feeling that may kill her lol The question requested for the mass of [ce]Na2CO3[/ce] not [ce]PbCO3[/ce]. Link to comment Share on other sites More sharing options...
EvoN1020v Posted October 29, 2005 Author Share Posted October 29, 2005 [Pb2+] = 1.5 x 10-5 mol dm-3 [Pb2+] > 1.0 x 10-9 is lethal Ksp of PbCO3 = 3.3 x 10-14 Volume of blood = 1.7 dm3 ~~~~~~~~~~PbCO3~~~~>> ~~~~~Pb2+ ~~~~+~~~CO32- Initial~~~~~~1.5 x 10~~~~~~~~~~~~y~~~~~~~~~~~ - Changes~~–(1.4999 x 10-5 )~~~–(1.4999 x 10-5 )~~~+(1.4999 x 10-5 ) Equilibrium~~~1.0 x 10-9~~~~ y –(1.4999 x 10-5 ) Ksp = [Pb2+][ CO32-] (1.0 x 10-9 ) (y –1.4999 x 10-5 ) = 3.3 x 10-14 y = 4.7999 x 10-5 no of mole of Na2CO3 = 4.7999 x 10-5 volume of blood Mass of Na2CO3 /106 = 4.7999 x 10-5 1.7 Mass = 8.65 x 10-3 g Is this correct ? You are using the ICE method' date=' very good. But you have an error in your calculation, because you know that the "change" for [ce']PbCO3[/ce] is -1.4999 x 10^5, therefore it should be positive over the other side. Your reply was –(1.4999 x 10-5 ). It should be positive. Also, please use "^" for exponents. I don't want to get confused. Secondly, what does "dm3" means? Link to comment Share on other sites More sharing options...
aommaster Posted October 29, 2005 Share Posted October 29, 2005 It stands for Dm^3 ie Decimeter Cubed Link to comment Share on other sites More sharing options...
EvoN1020v Posted October 29, 2005 Author Share Posted October 29, 2005 So Litre (L) is same as Dm^3? Link to comment Share on other sites More sharing options...
aommaster Posted October 29, 2005 Share Posted October 29, 2005 Well, yes. A decimeter cubed is (10cm)^3 and therefore 1000cm^3, which is a litre! Link to comment Share on other sites More sharing options...
EvoN1020v Posted October 29, 2005 Author Share Posted October 29, 2005 I disagree with you, because 1 L equals to 1,000 mL. But perhaps you are speaking of volume? Link to comment Share on other sites More sharing options...
aommaster Posted October 29, 2005 Share Posted October 29, 2005 Yeah, 1000mL is 1000cm^3 So basically, 1000mL=1000cm^3=1 litre Basically speaking, they are three different ways of speaking about the same thing! Thats science for you Link to comment Share on other sites More sharing options...
EvoN1020v Posted October 29, 2005 Author Share Posted October 29, 2005 Thanks. Now can anybody answer my chemistry question from post #1?? Link to comment Share on other sites More sharing options...
budullewraagh Posted October 29, 2005 Share Posted October 29, 2005 PbCO3 would precipitate in the blood and the girl would die Link to comment Share on other sites More sharing options...
blike Posted October 29, 2005 Share Posted October 29, 2005 This looks a lot like someone's homework. Link to comment Share on other sites More sharing options...
jdurg Posted October 30, 2005 Share Posted October 30, 2005 This looks a lot like someone's homework. I don't know about that. The question itself is kind of laughable at best, because you wouldn't inject a carbonate into anybody's blood to purposely ppt out a heavy metal. That would lead to a ppt forming in a critical capillary in various organs and result in almost certain death. In addition, the alkalinity of the carbonate ion could cause other problems. EDTA is typically used in a metal poisoning becuase it does bind with the heavy metal, but at the same time remains soluble in the blood so as not to cause blood vessel blockages. Link to comment Share on other sites More sharing options...
YT2095 Posted October 30, 2005 Share Posted October 30, 2005 This looks a lot like someone's homework. Agreed and I think the idea is to strip away the trivial data and boil it down to the equasion part, how much X is needed to "neutralise" Y. and not get caught up in malpractice suits Jdurg, Yeah EDTA and activated charcoal are the typical A&E procs Link to comment Share on other sites More sharing options...
insane_alien Posted October 30, 2005 Share Posted October 30, 2005 EDTA calculations of this sort are so simple. 1:1 stoichiometry Link to comment Share on other sites More sharing options...
EvoN1020v Posted October 30, 2005 Author Share Posted October 30, 2005 Seems like nobody here can answer my question Link to comment Share on other sites More sharing options...
budullewraagh Posted October 30, 2005 Share Posted October 30, 2005 once again, PbCO3 would precipitate in the blood and the girl would die Link to comment Share on other sites More sharing options...
EvoN1020v Posted November 1, 2005 Author Share Posted November 1, 2005 [Pb2+] = 1.5 x 10-5 mol dm-3 [Pb2+] > 1.0 x 10-9 is lethal Ksp of PbCO3 = 3.3 x 10-14 Volume of blood = 1.7 dm3 ~~~~~~~~~~PbCO3~~~~>> ~~~~~Pb2+ ~~~~+~~~CO32- Initial~~~~~~1.5 x 10~~~~~~~~~~~~y~~~~~~~~~~~ - Changes~~–(1.4999 x 10-5 )~~~–(1.4999 x 10-5 )~~~+(1.4999 x 10-5 ) Equilibrium~~~1.0 x 10-9~~~~ y –(1.4999 x 10-5 ) Ksp = [Pb2+][ CO32-] (1.0 x 10-9 ) (y –1.4999 x 10-5 ) = 3.3 x 10-14 y = 4.7999 x 10-5 no of mole of Na2CO3 = 4.7999 x 10-5 volume of blood Mass of Na2CO3 /106 = 4.7999 x 10-5 1.7 Mass = 8.65 x 10-3 g Is this correct ? I must quite frankly apologize to builgate because he got the correct answer. Congratulations builgate!! The answer I got was [math]8.6 x 10^-3 g[/math] after I figured it out. My method is a little different than what he did, so I will post my method for you guys tomorrow. (I promise it will be very clear). I don't have the time right now as I need to study for 2 Advanced Unit tests tomorrow, so wish me good luck! Link to comment Share on other sites More sharing options...
Halash Posted November 2, 2005 Share Posted November 2, 2005 Heh. So we'll ignore the fact that the precipitate would wind up blocking the arteries and veins in her brain and vital organs and kill her instantly? yeah i had a feeling that would happen Link to comment Share on other sites More sharing options...
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