Question

Situation:
A 40 gram sample of a substance thats used for drug research has a k-value of 0.1476.
N=Noe^-kt
No=initial mass( at time t=0)
N=mass at time t
k=a positive constant that depends on the substance itself and on the units used to measure time
t=time, in days

Find the substance's half-life,in days.Round your answer to the nearest tenth.

Answer 1

these questions are all the same. what you are looking for is the time when N=No/2. if you sub that in you get No/2=N0e^-kt. the No's cancel and solving for t you get
t=-ln(0.5)/k

Answer 2

as you can see the answer is independent of the initial mass which is a characteristic of half-lives

Answer 3

i have to find the substances half like in days

Answer 4

so as you can see the t value when calculated will give you the time in days as the k value adjusts for this so if you plug the solution into a calculator you get 4.69611... rounded to the nearest tenth you get 4.7 days

Answer 5

formula for half life=(ln2)/k
=(ln2)/0.1476=4.7 approximately

Answer 6

thankssssss

Answer 7

can u guys help me with the next question?

Answer 8

4.7