Question

A patient recieves 9.0 ng of a radioisotope with a half-live of 12 hours. How much will remain in the body (in ng) after 2.0 days?

Answer 1

Approximately `0.563ng` of the described radioisotope will remain in two days within the patient's body.

Explanation:

`ln(([A]_t)/([A]_0)) = -kt`

`t_(1/2) = 0.693/k`

`-----`

`12h = 0.693/k`
`therefore k approx 5.78*10^-2h^-1`

`ln(([A]_(2d))/(9.0ng)) = -5.78*10^-2h^-1 * 2.0d * (24h)/(d)`
`therefore [A]_(2d) approx 0.563ng`