Problem: A moon rock collected by a U.S. Apollo mission is estimated to be 4.30 billion years old by uranium/lead dating. Assuming that the rock did not contain any lead when it was formed, what is the current mass in grams of  206Pb per 1.260 g of  236U in the rock? The half-life of  236U is t1/2 = 4.47 x 109 years.

FREE Expert Solution
97% (463 ratings)
FREE Expert Solution

We’re being asked to determine the mass of 206Pb in a moon rock with 1.260 g 236U

Recall that radioactive/nuclear decay of isotopes follows first-order kinetics, and the integrated rate law for first-order reactions is: where:

[N]t = concentration at time t

k = decay constant

t = time

[N]0 = initial concentration

Also, recall that half-life is the time needed for the amount of a reactant to decrease by 50% or one-half

The half-life of a first-order reaction is given by: 97% (463 ratings)
Problem Details

A moon rock collected by a U.S. Apollo mission is estimated to be 4.30 billion years old by uranium/lead dating. Assuming that the rock did not contain any lead when it was formed, what is the current mass in grams of  206Pb per 1.260 g of  236U in the rock? The half-life of  236U is t1/2 = 4.47 x 109 years.

What scientific concept do you need to know in order to solve this problem?

Our tutors have indicated that to solve this problem you will need to apply the First Order Half Life concept. You can view video lessons to learn First Order Half Life Or if you need more First Order Half Life practice, you can also practice First Order Half Life practice problems .

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Based on our data, we think this problem is relevant for Professor Ren's class at PURDUE.