Question

11. My Notes Ask Your Teacher -/10 points Content Carbon dating An archaeologist finds some ancient jewelry made from bone. The jewelry has a carbon mass of 435 g (HINT: Assume all the carbon is 12C and determine the number of atoms) and careful measurements show that the remaining 14C has a current decay rate of 11 decays/s. Determine the age of the bone (and presumably the jewelry). Remember, the ratio of 14C to 12C when the animal died was 1.3x10- 12 & the half-life of 14C is 5730 y. age of bone = Rubidium-Strontium dating A geologist finds an old rock and wants to determine its age using rubidium- strontium dating. This is possible because 87Rb, which has a half-life of 4.75x1010 y, undergoes B-decay and becomes 87Sr. The geologist determines that the ratio of 87Sr to 87Rb is 0.35. Assuming there was no 87 Sr in the rock when it was formed, determine the age of the rock. age of rock = 0 Submit Answer Submit Assignment Save Assignment Progress

Answer 1

Carbon dating 0,693 xt 5730 2.868 X 10 12 2.838 1013 e 435g = n* mass of the atom, a Nor 10 9927 x 10-23 Cg) atoms 9.9./12 2,183 x 1025 (Total) = No = - 0.693 xt 5730 t = TE 19,000 Years 18,960 years ] No of atoms of 146 when animal died No = 2, 838 X1013 ty = 57304 activity Equation (3) - N= No e n - 0 - 0.693 N- AN = -XN - TY At Rubidium - strontium T=o Rb Sr 2004. 0% dating T= T. years sr=0.5 Rb 65% of N 0.693 XT Natoms - 0.65 = e 4.75% 1010 from @ we can find N I= 2.95 x 100 years 11= 0.693 x N e 5730 X (see and in year) 11 = N 0.693 X 1.8074 101 N = N 2.868 x 102 in eq 0 Putting