Question

Barium – 122 has a half-life of 2 minutes. Suppose you obtain a sample weighing 20.0 g and it takes 10 minutes to set up an experiment. How many grams of Barium – 122 will remain at the point when you begin the experiment?

Answer 1

Answer:
0.3125 g
Step-by-step explanation:
Given data:
Half life of barium-122 = 2 min
Mass of sample = 10.0 g
Mass of barium remain after 10 min = ?
Solution:
Number of half lives = Time elapsed / half life
Number of half lives = 10 min/ 2 min
Number of half lives = 5
At time zero = 10 g
At 1st half life = 10 g/2 = 5 g
At 2nd half life = 5 g/2 = 2.5 g
At 3rd half life = 2.5 g/2 = 1.25 g
At 4th half life = 1.25 g/2 = 0.625 g
At 5th half life = 0.625 g/2 = 0.3125 g