Question

A uranium mineral contains ${}^{238}U$ and ${}^{206}Pb$ in the ratio of $4:1$ by weight. Calculate the age of the mineral, $t_{1/2}$ ${}^{238}U=4.5\times {10}^9$ years. Assume that all the lead present in the mineral is formed from disintegration of ${}^{238}U$.

Answer 1

$t=\frac{2.303}{0.693}\times 4.5\times {10}^9\times log(1+\frac{1/206}{\frac{4}{238}})$

$t=1.64\times {10}^9$ years