IMG_0004_NEW_0021

IMG_0004_NEW_0021 - -frt kr[A]o So,kr[2:ktyz-ffi Half Life...

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Example: 1"t Order Rate Law 2N2O5 -+ 4NO2 + 02 Question l: Is this a First-Order Reaction? Question 2: What is the rate constant? Answer: We can't tell without an experiment! + Measure how concentration varies with time: Rat" = - dlNzo'l = t[N,o,l dt ...if it's fust order hard to tell from [NzOr] vs Time How to determine fr? l0 20 T:@(s) Plot: ln[NrOr] vs Time First order: ln[NrOr] : -h + ln[NrOr]o Straight line? = l't order sloPe: -k 5 0.10 0.00 0lr 0.04 0.o2 ofr -3.() d i {.m a .g -5.0 l(. m 3m ,(! Tnc(s) Half-life of lst Order Reactions . Definition: Half-life Half-life : time taken for concentration to fall to half its original value. . aA -+ products Rate= #=urot and Therefore^ hrfl l \ r wi)=o' when rAr=ry ,r[#)=0,,, hr[a]=
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Unformatted text preview: -frt+kr[A]o So,kr[2]:ktyz-ffi Half Life or a.Qj,brder--Reaction 2N2O5+4NO2+02 lN,o,L-o o,$o o.(xD ogrfl) o_lm ] lxgL-o.oco i:. t 'oo-0.o3n hiro'L-4 o,o:(n E;ot--*r, 50 0 L50 :tI) a50 3$ ,150 100 ,t: f!: lv= Tm(sl 4L.--100s Half Lives: Radioactivity . Example: Decay of Polonium 210Po -+ 206Pb + aHe (alpha radiation) . Radioactive Decay: First Order process t r,r(ztoP o) : I 3 8.376 days . Minimum lethal dose - I pg for 80 kg person . Excreted in -30 - 50 days Former KGB agent Alexander Litvinenko Dose: l0 pg (@ $l million per pg) . Compare with 238U' 238U -) 234Th + 4He . Half life : 4.5 billion years = much lower toxicity Before After...
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This note was uploaded on 12/27/2011 for the course CHEM 122 taught by Professor Williams during the Fall '10 term at Simon Fraser.

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