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Tema [17]
3 years ago
13

A geological sample is found to have a Pb-206/U-238 mass ratio of 0.337/1.00. Assuming there was no Pb-206 present when the samp

le was formed, how old is it? The half-life of U-238 is 4.5 × 109 years.
Chemistry
2 answers:
DENIUS [597]3 years ago
5 0

Answer:

7.1 x 10^9 years

Explanation:

This is the answer according to Mastering Chemistry.

azamat3 years ago
4 0

Answer:

Age=2.52*10^9 years

Explanation:

To determine the age, we need to know how much U have become Pb, so first we have to calculate the Pb moles present in a sample:

n_{Pb}=\frac{0.337g}{206g/mol}=0.00164 mol

n_{U}=\frac{1 g}{238g/mol}=0.0042 mol

The percentage of U degradation:

P=\frac{n_{Pb}}{n_{Pb}+n_{U}}

P=\frac{0.00164}{0.00164+0.0042}=0.28

Assuming that the life time is linear:

Age=\frac{4.5*10^9 years}{0.5 life time}*0.28 life time

Age=2.52*10^9 years

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8 0
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8 0
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