This one is half-life I know but I cannot figure out how to go through it, it isn't finding the amount so none of the examples my teacher gave me can show how to move things around...any help is appreciated.
The half-life of sulfur-138 is 4 days. After 12 days,a sample of this radioactive material has been reduced to a mass of 0.64g.
a) What is the initial mass?
b) What is the mass after 2 days?
Also if it wouldn't hurt could someone could walk through it, if not then just show all the steps to solve it.
Formulæ for half-life in exponential decay
Main article: Exponential decay
An exponential decay process can be described by any of the following three equivalent formulae:
Nt = N0e − t / τ Nt = N0e − λt where
You've got , and
- N0 is the initial quantity of the thing that will decay (this quantity may be measured in grams, moles, number of atoms, etc.),
- Nt is the quantity that still remains and has not yet decayed after a time t,
- t1 / 2 is the half-life of the decaying quantity,
- τ is a positive number called the mean lifetime of the decaying quantity,
- λ is a positive number called the decay constant of the decaying quantity.
and
so
What's eight times 0.64?