Question

Question on decay and half life?

Answer 1

@TuringTest could you help me?

Answer 2

So at t = 0 there is no Argon 40

Answer 3

Use the decay equation

\[N = N_oe^(\frac{-t}{\tau})\]

where,

\[\tau = \frac{t_{\frac{1}{2}}}{\ln(2)}\]

Answer 4

K 40 and Ar 40 have the same mass so their molar mass are the same, thus the question gives you the initial amount of K 40

Answer 5

I made a mistake -t/tau should be an exponent to e

Answer 6

Can you solve this now?

https://en.wikipedia.org/wiki/Exponential_decay#Half-life

The formula I posted is found here, if you dont understand what I mean -t/tau should be an exponent e

tau by the way (the weird looking t) is the mean lifetime of the element

Answer 7

Possibly... it would have been so nice if someone had clarified that earlier...

Answer 8

Actually, I still don't get it. Which is the initial amount of K? 1.41?

Answer 9

Too late... time's up. :x Thanks a lot for trying

Answer 10

Too late for what? You dont want help anymore? I'm not here to solve it for you I'm here to help you solve it

Answer 11

Time up for the assignment

Answer 12

It was due at 6, now it's 6:02

Answer 13

It submits automatically and I can't change my answers

Answer 14

I'm aware of how online assignments work, all you had to do is use the equation above and add the moles of K 40 to the moles of Ar 40 then plug them into that formula with the final amount of K40, oh and find what Tau was which was easy to do you had the half life

Answer 15

But I didn't know which numbers to plug in where in the equation (I was also trying to do other questions as you were explaining it)

Answer 16

mmol is moles?

Answer 17

no that is millimoles it is just moles/1000

Answer 18

you dont have to convert to moles it doesnt matter you just need to find t in that equation,

t = time

Answer 19

Oh... yeah I didn't know that either. I just started a college chem course and he's going all over the place, our homework isn't what we learn in class and our labs are different too. I guess we're kind of expected to remember stuff from high school chemistry but that was two years ago and I didn't do so well then either...

Answer 20

I don't know what to tell you, just learn how to use exponential decay formula, you will probably see it in calc and maybe physics

Answer 21

I made an assumption to answer that problem that,

\[K^{40} -> Ar^{40} + somethingelse\]

That something else will just be a photo or some other stuff, (I really need to review particle physics blah)

Answer 22

but yeah you probably know how to answer it now if you can do basic algebra

Answer 23

So is tau 1803368801?