6C.8 The half-life for the (first-order) radioactive decay of 14C is 5730 a (1 a is the SI unit 1 annum, for 1 year); the nuclide emits ẞ particles, high-energy electrons, with an energy of 0.16 MeV). An archaeological sample contained wood that had only 69 per cent of the 14C found in living trees. What is its age?

6C.8 The half-life for the (first-order) radioactive decay of 14C is 5730 a (1 a is the SI unit 1 annum, for 1 year); the nuclide emits ẞ particles, high-energy electrons, with an energy of 0.16 MeV). An archaeological sample contained wood that had only 69 per cent of the 14C found in living trees. What is its age?

Chemistry: Matter and Change

1st Edition

ISBN:9780078746376

Author:Dinah Zike, Laurel Dingrando, Nicholas Hainen, Cheryl Wistrom

Publisher:Dinah Zike, Laurel Dingrando, Nicholas Hainen, Cheryl Wistrom

Chapter24: Nuclear Chemistry

Section: Chapter Questions

Problem 82A

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The rate constant for the radioactive decay of 14C is 1.21104 year-1. The products of the decay are nitrogen atoms and electrons (beta particles): C614N714+e rate =k[C614] What is the instantaneous rate of production of N atoms in a sample with a carbon-14 content of 6.5109M?
Recently, the skeleton of King Richard III was found under a parking lot in England. If tissue samples from the skeleton) contain about 93.79% of the carbon-14 expected in living tissue, what year did King Richard III die? The half-life fur carbon-14 is 5730 years.
Fluorine-18 is a radioactive isotope that decays by positron emission to form oxygen-18 with a half-life of 109.7 min. (A positron is a particle with the mass of an electron and a single unit of positive charge; the equation is F918O188+e+10 Physicians use 18F to study the brain by injecting a quantity of ?uoro-substituted glucose into the blood of a patient. The glucose accumulates in the regions where the brain is active and needs nourishment. (a) What is the rate constant for [lie decomposition of ?uorine-18? (b) If a sample of glucose containing radioactive fluorine-18 is injected into the blood, what percent of the radioactivity will remain after 5.59 h? (c) How long does it take for 99.99% of the 18F to decay?
If 1.000 g of R88226a produces 0.0001 mL of the gas R86222n at STP (standard temperature and pressure) in 24 h, what is the half-life of 226Ra in years?
The rate of photodecomposition of the herbicide piclo- ram in aqueous systems was determined by exposure to sunlight for a number of days. One such experiment produced the following results. (Data from R.T. Hedlun and C.R. Youngson, “The Rates of Photodecomposition of Picloram in Aqueous Systems," Fate of Organic Pesticides in tbe Aquatic Environment, Advances in Chemistry Series, #111, American Chemical Society (1972), 159—172.) Exposure Time, t (days) [Pidoram] (mol L_1) 0 4.14 X 10-6 7 3.70 X 10-6 14 3.31 X 10-6 21 2.94 X 10~6 28 2.61 X 10~6 35 2.30 X 10-6 42 2.05 X 10-6 49 1.82 X 10"6 56 1.65 X 10-6 Determine the order of reaction, the rate constant, and the half-life for the photodecomposition of picloram.
The half-life of tritium, 3H, is 12.26 years. Tritium is the radioactive isotope of hydrogen. (a) What is the rate constant for the radioactive decay of tritium, in y1 and s1? (b) What percentage of the original tritium is left after 61.3 years?
The half life for the radioactive decay of potassium-40 to argon-40 is 1.26 x 10 years. Suppose nuclear chemical analysis shows that there is 0.543 mmol of argon-40 for every 1.000 mmol of potassium-40 in a certain sample of rock. Calculate the age of the rock. Round your answer to 2 significant digits. years Ox10 ?
An atomic isotope radioactively decays and has a half-life of 23.7 days. How many days will it take for 88.2% of the sample to decay? In([A]MA]) = -kt t1/2 = (In2/k) 券 (1/[A]) = kt + (1/AI,) t1/2 (1/k[A],) [A]=-kt + [Alo t1/2 = ([A]/2k) In(k2/kq) = (E/R)[(1/T;)- (1/T2)] R= 0.0820573L atm/(K mol) उस R = 8.31446 J 7(K mol) Type your answer in the space below without the units.