the initial concentration of XY is 0.225 mol·L−1, how long will it take for the concentration to decrease to 6.95 × 10−2 mol·L−1 ?. Half life (t1/2)= 1336s or 1.336x103

. The half-life of thallium−201 is three days. What fraction of thallium−201 is still present in an individual after twelve days? (Report your answer in fraction format.)

Two gases X and Y are found in the atmosphere in only trace amounts because they decompose quickly. When exposed to ultraviolet light the half-life of X is 105. min, while that of Y is 1.25 h. Suppose an atmospheric scientist studying these decompositions fills a transparent 20.0 L flask with X and Y and exposes the flask to UV light. Initially, the partial pressure of X is 5.0 times greater than the partial pressure of Y. As both gases decompose, will the partial pressure of X ever fall below the partial pressure of Y? If you said yes, calculate the time it takes the partial pressure of X to fall below the partial pressure of Y. Round your answer to 2 significant digits. yes no min x10 X = S ?

In a study of the formation of HI from its elements, H2(g) + 12(g) == 2HI(g) equal amounts of H2 and 12 were placed in a container, which was then sealed and heated. (a) On one set of axes, sketch concentration vs. time curves for H and HI, and explain how Q changes as a function of time. (b) Is the value of Q different if [12] is plotted instead of [H2]?

A suggested mechanism for the gas phase decomposition of nitrous oxide is: step 1: NgÐ — Nz + 0 N₂O + O N₂ + O2 step 2: (a) Identify the molecularity of each step in the mechanism. step 1 8 step 2 (b) Write the equation for the net reaction. Use the smallest integer coefficients possible. If a box is not needed, leave it blank. 8 (c) Identify any intemediates and/or catalysts in this mechanism. Catalyst: Enter formula. If none, leave box blank: Intermediate: Enter formula. If none, leave box blank: The following mechanism has been proposed for the gas phase reaction of nitrogen monoxide with bromine. step 1: NO + Br₂ → NOBr₂ NOBr₂ + NO 2 NOBr step 2: (a) Identify the molecularity of each step in the mechanism. step 1 step 2 (b) Write the equation for the net reaction. Use the smallest integer coefficients possible. If a box is not needed, leave it blank. (c) Identify any intermediates and/or catalysts in this mechanism. Catalyst: Enter formula. If none, leave box blank: Intermediate:…

3. One of the radioactive nuclides formed in nuclear power plants is hydrogen-3, called tritium, which has a half-life of 12.26 years. How long before a sample decreases to 1/8 of its original amount?

Scientists can determine the age of ancient objects by the method of radiocarbon dating. The bombardment of the upper atmosphere by cosmic rays converts nitrogen to a radioactive isotope of carbon, 14C, with a half-life of about 5,730 years. Vegetation absorbs carbon dioxide through the atmosphere, and animal life assimilates 14C through food chains. When a plant or animal dies, it stops replacing its carbon, and the amount of 14C present begins to decrease through radioactive decay. Therefore, the level of radioactivity must also decay exponentially.   a) Dinosaur fossils are too old to be reliably dated using carbon-14. Suppose we had a 67 million year old dinosaur fossil. What percent of the living dinosaur's 14C would be remaining today? (Round your answer to five decimal places.)   b) Suppose the minimum detectable amount is 0.7%. What is the maximum age (in years) of a fossil that we could date using 14C? (Round your answer to the nearest year.)

Two gases X and Y are found in the atmosphere in only trace amounts because they decompose quickly. When exposed to ultraviolet light the half-life of X is 15. min, while that of Y is 1.75 h. Suppose an atmospheric scientist studying these decompositions fills a transparent 10.0 L flask with X and Y and exposes the flask to UV light. Initially, the partial pressure of X is 50.0% greater than the partial pressure of Y. As both gases decompose, will the partial pressure of X ever fall below the partial pressure of Y? If you said yes, calculate the time it takes the partial pressure of X to fall below the partial pressure of Y. Round your answer to 2 significant digits. 0 yes no min x10 X 010 Ś 00c 18 Ar DI

Radioactive gold-198 is used in the diagnosis of liver problems. The half-life of the isotope is 2.7 days. If you begin with 5.6 mg of the isotope, how many days will it take for the quantity of gold-198 to be 0.70 mg?

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