Half Life / Alpha Decay Question - No IDea

[wayneinsane]

Half Life / Alpha Decay Question -- No IDea

Homework Statement

A space rock contains 3.20 g of 147 62 Sm and 0.110 g of 143 60 Nd. 147 62 Sm alpha decays to 143 60 Nd with a half-life of 1.06 1011 yr. If the rock originally contained no , how old is it?

Homework Equations

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The Attempt at a Solution

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[LowlyPion]

If you presume that it was all samarium with no neodymium, then all you need to do is apply the decay formula to the original sample as though all the mass was samarium. (Now it's true that the alpha particles emitted represent a loss of mass, but I'd think since the neodymium is a minor fraction of the samarium you can ignore the loss.)