Chemistry
posted by Steven .
A 50.6 mg sample of sodium perchlorate contains radioactive chlorine36 (whose atomic mass is 36.0 amu). If 29.6% of the chlorine atoms in the sample are chlorine36 and the remainder is naturally occurring nonradioactive chlorine atoms, how many disintegrations per second are produced by this sample? The halflife of chlorine36 is 3.5*10^5 yr.

moles NaClO4 = grams/molar mass
moles Cl atoms = moles NaClO4.
# Cl atoms = moles Cl atoms x 6.02E23 atoms/mol.
Multiply by 0.296 to find the number that are radioactive.
rate = k*No where No = number Cl atoms
k can be determined from k = 0.693/t_{1/2} and the units are Yr^2 since the half life is in years.
Therefore, the rate you calculate will be the decays per year. Convert that to dps.