Radiocarbon dating of a piece of wood

[Lindsayyyy]

Hi

Homework Statement

A lance of wood is found wheres one piece contains 2,70 g 12^C. A scintillation counter shows 27,3 radiactive decay per minute.

How old is the lance?

Homework Equations

$$N(t)= N_0 \cdot e^{-\lambda t}$$

maybe half life of 14^C : 5730 years.

The Attempt at a Solution

My attempt was using the above equation, I have nothing else given (like mass of a C atom etc). My problem is I think I am missing some information. I tried to get to the solution by using the relative ratio of 12C and 14C but I read that this only counts for living organisms. Is it even possible to solve this without any further information? Sorry for such a short attempt at a solution but I have no idea, wasn't even able to find something which helps me and I really like to understand that problem.

Thanks for your help

 

[gneill]

It looks like the problem is solvable if you take into account an assumption of the original ratio of C14 to C12. The measured decay rate should tell you the current number of atoms of C14 remaining in the sample.

 

[Office_Shredder]

I tried to get to the solution by using the relative ratio of 12C and 14C but I read that this only counts for living organisms.

One example of a living organism is the tree that the wood came from

 

[Lindsayyyy]

but wood is a "dead" organism :). I though I am not allowed to use that information for dead objects. I think I can solve it than, thanks.

 

[gneill]

but wood is a "dead" organism :). I though I am not allowed to use that information for dead objects. I think I can solve it than, thanks.

Wood is dead as soon as the tree dies. That's when its radiocarbon clock starts ticking, as the "living" C14/C12 ratio is no longer maintained by constant replenishment though metabolism.