Question

The activity of a radioactive sample is the
number of nuclear disintegrations per second,
which is equal to the first-order rate constant times
the number of radioactive nuclei present. The
fundamental unit of radioactivity is the curie (Ci),
where 1 Ci corresponds to exactly 3.70 x 1010
disintegrations per second. This decay rate is
equivalent to that of 1 g of radium-226. Calculate
the rate constant and half-life for the radium
decay. Starting with 1.0 g of the radium sample,
what is the activity after 500 yr? The molar mass of
Ra-226 is 226.03 g/mol?

Answer 1

k= 1.4 x 10-11

t1/2= 5 x 10^10

Activity after 500 years = 3.1 x 10 ^10