Question

Question 1: Answer the following questions regarding half-lives. Assume first-order half life kinetics (2 pts total). A. The half-life of Co-60 is about 5.25 years. Starting with a 42 g sample, how much remains after 21.0 years have passed (1 pt)? B. The Spider that bit Miles Morales secretes an unknown radioactive chemical that decays via first order kinetics. Originally 27.0 mg, only 5.3 mg remains after 32 days. What is this compound's half-life (1 pt)?

Answer 1

1 For any reaction, Halk life is the beriod ich the time interval in which conc. of reactant becomes half of its initial value. I A 112 A0/2 12 A0/4 1/2 A/B For est order ron, tuz is constant A.) = 5.25 years Half lines completed in 21 years = 2 1 1 2 = 4 Remaining amount of reactiot = 24 5.25 24 6416 = 2.625 g,

- A = 27mg tored on 2 rumaining amount @ 295.3 mg a 32 For first order ron & more log ætlases 2.303 hits UND ti t ly. 2.303 it pose logromno 0633.6 log 210.693 x32 moret 2.303 7/2 0.693 x32 2.33 X log 2 1 2 OMX Stoc 22.176 2.3038 0.7071 = 13.62 days SEHP