It is determined to have a half-life of 100 years.What time is required to reduce an activity of 7.0 x 1012 disintegrations per min (dpm) to a harmless activity of
2 x10-3 dpm?
2007-07-09 06:14:14 · 3 answers · asked by its me 1 in Science & Mathematics ➔ Chemistry
What divisor reduces 7x10^12 to 2x10^(-3)? 2 to what power is that number? Said exponent (doesn't need to be an integer) is the number of half-lives you need.
How patient are you? When does the sun bloat?
2007-07-09 06:34:26 · answer #1 · answered by Uncle Al 5 · 1⤊ 0⤋
A=A0*2^(-t/T)
A=2*10^-3 A0 =7*10^12
So 2*10^-3/7 *10^12= 2^(-t/T)
2^(t/T) =7*10^12/2*10^-3 =3.5*10^15
t/T =log2 3.510^15=51.636and as T=100
answer t=5163min=86.1hours
2007-07-09 14:28:54 · answer #2 · answered by maussy 7 · 0⤊ 1⤋
forumla is -(half life)*( ln ( final / initial) ) = time
ends up being about 3580 years.
2007-07-09 14:50:09 · answer #3 · answered by Koozie the chemist 4 · 0⤊ 0⤋