The half-life for the (first order) radioactive decay of 14C is5730
years. An archeological sample
contained wood with only 72% of the 14C found in living trees.
Whatwas the age of this archeological sample?

Respuesta :

Answer:

The age of this archeological sample is 2737.53 years

Explanation:

Given that:

Half life = 5730  years

[tex]t_{1/2}=\frac {ln\ 2}{k}[/tex]

Where, k is rate constant

So,  

[tex]k=\frac {ln\ 2}{t_{1/2}}[/tex]

[tex]k=\frac{\ln\ 2}{5730}\ year^{-1}[/tex]

The rate constant, k = 0.00012 year⁻¹

Using integrated rate law for first order kinetics as:

[tex][A_t]=[A_0]e^{-kt}[/tex]

Where,  

[tex][A_t][/tex] is the concentration at time t

[tex][A_0][/tex] is the initial concentration

Given that:

The rate constant, k = [tex]0.00012[/tex] year⁻¹

It is given that 72 % of the 14C remains. So,

[tex]\frac {[A_t]}{[A_0]}[/tex] = 0.72

Applying values as:-

[tex]\frac {[A_t]}{[A_0]}=e^{-k\times t}[/tex]

[tex]0.72 =e^{-0.00012\times t}[/tex]

[tex]\ln \left(0.72\right)=-0.00012t\ln \left(e\right)[/tex]

[tex]\ln \left(0.72\right)=-0.00012t[/tex]

[tex]t=2737.53\ years[/tex]

The age of this archeological sample is 2737.53 years