Question

A half-life of 82Br nucleus is about 1.0 × 103 minutes. If you wanted 3.6 g of Br-82 and the delivery time was three days, about how much sodium bromide should you order (assuming all of the Br in the NaBr was 82Br)?

Answer 1

Hope you will like my answer.

initially be x in NaBr Let the mass of Br 82 Desired mass of Br - 82 after 3 days 3.68 Moles o Br- 82 intially 82 of Br-32 after 3-day - 3. 6 Moles 82 O 693 O.693 K O.693 min- 10 X 103 (t3days ১ No Log t - 2. 303 3x60 x 24 min) 2-30 3x I0 Xo3 3 x 24 X 60 ০693 3x 24 x60 x o 693 1 2 303 x 1 0 103 161.3 3.6 n=71-82 9 Molar mass of Na Br x mass o Br initally Mass of Na Br Molar mass of Br 10 5 7 1 829 82 91. 9 8 9219 ec 20 22

Answer 2

Given:
Half life = 1*10^3 min
use relation between rate constant and half life of 1st order reaction

k = (ln 2) / k
= 0.693/(half life)
= 0.693/(1*10^3)
= 6.93*10^-4 min-1

we have:
[A] = 3.6 g
t = 3 days
= 3*24*60 min
= 4320 min
k = 6.93*10^-4 min-1

use integrated rate law for 1st order reaction
ln[A] = ln[A]o - k*t
ln(3.6) = ln[A]o - 6.93*10^-4*4.32*10^3
ln[A]o = 1.281 + 6.93*10^-4*4.32*10^3
ln[A]o = 4.275
[A]o = e^(4.275)
[A]o = 71.9 g
Answer: 72 g