What is the half-life of a radioisotope if 25.0 grams of an original 200.-gram sample of the isotope remains unchanged after 11.46 days? (1) 2.87 d (3) 11.46 d (2) 3.82 d (4) 34.38 d
Chemistry · High School · Tue Nov 03 2020
llm
Answered on
Given :
K = rate constant
time taken for decay process, t = 11.46 days
Initial amount of the reactant, a = 200 grams
Amount of reactant after decay process, a - x = 25 grams
Formula :
K = 2.304/t log(a/a-x)
K = 2.303/11.46 log(200/25)
K = 0.1814
Now, half life of radioisotope
t½ = 0.693/K
= 0.693/0.1814
= 3.820
Hence, half life of radioisotope is 3.820 days.