Question

The disintegration of a radioisotope, such as I-131 to Xe-131, is another example of a first-order reaction.
It has a half-life of 8.0 days.

I-131 -> Xe-131 + e

If you start with 1.40 g I-131, how many grams of I-131 will be left after the following days?

08 days: g,
16 days: g,
20 days: g,
24 days: g,
30 days: g
32 days: g
47 days: g

Answer 1

k = 0.693/t_1/2
Then ln(No/N) = kt
No = 1.41 g
N = ?
k = from above
t = 8 days for #1.

The others are done the same way. Solve for N.

Answer 2

Hhf