Unit X: Nuclear Chemistry CHE 102 Course Manual 15. A pet rock cannot be dated with...
Unit X: Nuclear Chemistry CHE 102 Course Manual 15. A pet rock cannot be dated with C-14. However, it might be dated from its content of K-40. A sample of rock was found to contain 3.45 x 10-4 mole of K- 40 and 2.27 x 10-4 mole of Ar-40. If we assume that all of the Ar-40 (a gas) escaped until the molten lava turned solid, and that all of the Ar-40 came from Page 283 the decay of K-40, what is the age of the rock in years? (t1/2 = 1.3 x 109 years for K-40) ANS: 9.6 x 108 yrs.