Apply half life equation
A = A0*(1/2)^(t/hl)
A = A0 *(1/2)^(t/(4.7*10^10))
the decay:
87Rb = 87Sr + beta
mol of Sr = 4.3/69.90888 = 0.06150863
mol of Rb = 104.2/86.90919 = 1.19895
total mol = 1.19895+0.06150863 = 1.260459
now..
substitute
1.19895 = 1.260459*(1/2)^(t/(4.7*10^10))
solve for t
ln(1.19895 /1.260459) / ln(0.5) = t / (4.7*10^10)
t = (4.7)*ln(1.19895 /1.260459) / ln(0.5) * 10^10
t = 0.33923*10^10
then
t = 3.39*10^9 years old
1010 years. What is the age of a rock sample that contains 1042 ug Rubidum 87...
Rubidium-87 decays by ß production to strontium-87 with a half life of 4.7 x 1010 years. What is the age of a rock sample that contains 104.9 ug 7Rb and 4.3 ug 87Sr? years old Assume that no 87Sr was present when the rock was formed. The atomic masses are given in the table below: Nuclide Atomic Mass 87Rb 86.90919 87Sr 86.90888
Rubidium-87 decays by β production to strontium-87 with a half life of 4.7 × 1010 years. What is the age of a rock sample that contains 109.7 µg 87Rb and 4.0 µg 87Sr ? ___ years old Assume that no 87Sr was present when the rock was formed. Nuclide Atomic Mass 87Rb 86.90919 87Sr 86.90888
WILL RATE CORRECT ANSWERS
CHEMWORK Rubidium-87 decays by B production to strontium-87 with a half life of 4.7 x 1010 years. What is the age of a rock sample that contains 109.4 ug 87Rb and 5.5 87Sr? ug years old Assume that no 87 Sr was present when the rock was formed. The atomic masses are given in the table below: Nuclide Atomic Mass 87 RB 86.90919 87$ 86.90888
CHEMWORK Rubidium-87 decays by B production to strontium-87 with a half life of 4.7 x 1010 years. What is the age of a rock sample that contains 109.8 ug 87Rb and 4.8 ug 87 1Sr? years old Assume that no 875r was present when the rock was formed. The atomic masses are given in the table below: Nuclide Atomic Mass 87Rb 86.90919 8781 86.90888 Submit Show Hints
The 87Rb rubidium isotope is used to determine the age of rocks and fossils. 87Rb is β-active with a half-life of 4.9 to 1010 years and is degraded to strontium isotope 87Sr. The fossil under study contains strontium in the ratio k = NSr / NRb = 0.0055. Calculate the age of the fossil by assuming that strontium was not present when the fossil was petrified. Give the answer in years (ie a).
4) An igneous Martian meteorite contains four different minerals with the following isotopic compositions: Mineral Covidite Trumpite Insleeite Faucite 87Rb/86Sr 10 7.00 5.00 2.00 87St/86Sr 1.12 0.101 0.89 0.79 86Sr and 878r are stable isotopes but 87Rb is radioactive and decays to 875r with a decay constant (time to decay by e-?) of 7 x 1010 years. When the minerals formed by crystallization from a liquid they had identical 875r/86Sr ratios. Plot the data on a graph of 87Sr/86Sr (y...
21.42
for the beta decay of 130TI? OBJECTIVE Determine the ages of samples of matte from radioactive decay data. 21.41 A sample of uranium ore contains 6.73 mg 238U and 3.22 ,206Pb. Assuming that all of the 206Pb arose from decay mg of the 238U and that the half-life of 23U is 4.51 × 10° years, determine the of the ore. age 21.42 A tree was cut down and used to make a statue 2300 vears ago. What fraction of...