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In a paper by Bada, Protsch, and Schroeder [Nature 241:394, 1973], the rate of isomerization of isoleucine in fossilized bone is used as an indication of the average temperature of the sample since it was deposited. The reaction L-isoleucene ↔D-alloisoleucine, (shortened to iso↔allo), produces the noncanonical amino acid D-alloisoleucine that can be measured using an automatic amino acid analyzer. At 293 K, this first-order reaction has a half-life of 125,000 years, and its activation energy is 139.7 kJ/mol. After a very long time, the ratio of allo/iso reaches an equilibrium value of 1.38. You may assume that this equilibrium constant is temperature independent. a. For a hippopotamus tooth found near a warm spring in South Africa, the allo/iso ratio was found to be 0.42. Assuming that no allo was present initially, calculate the ratio of the concentration of allo now present to the concentration of allo after a very long time. The correct answer is between 0.4 and 0.6. (Hint: figure the amount of allo present in terms of the amount of iso when the hippo died at the present time and at very long times.) b. Radiocarbon dating, which is temperature independent, indicated an age of 38,600 years for the hippo tooth. Using the result from part a), estimate the half-life for the process. c. Calculate the average temperature of this specimen during its residence in the ground. (The present mean temperature of the spring is 301 K.)
Show why this chemical is dangerous, by showing chemical reactions for its formation in the environment and its reactions in the atmosphere.
The following data apply to 25oC and 100kPa. Assume the specific volume Vs, and Kt are constant with respect to pressure changes. delta G(graph) = 0
When aluminum metal is dipped in an aqueous solution of hydrochloric acid, hydrogen gas is produced with the formation of an aluminum chloride solution. Write the balanced chemical equation showing the phase of reactants and products.
1.25g sample of a benzoic acid with a heat capacity of 25.0kjgwas burned in a bomb calorimeter and the temperature of
calculate the mole fraction of soluteand solvent present in the solution.
At 800 k, Kc for the following equalibrium is 4.2 x 10 ^-3. 2HgO(s) 2Hg(l) + O2(g), suppose 96.5 g of mercury(ll) oxide is placed in a sealed 3.50 vessel at 800 k. What is the partial pressure of oxygen gas at equalibrium
A direct current was passed through a solution containing alanine, Match the behavior with correct amino acid. The isoelectric point of histidine is 10.0.
A reaction in which A,B ,C and react to form products is first order in A, second order in B, and zero order in C. What is the overall order of the reaction?
Hydrolysis of an ester using sodium hydroxide (2M) is usually a fast reaction. Why would it take almost 40 minutes to complete? It is imperative to consider the location of each reagent within the vial.
Monochloroacetic acid (HC2H2ClO2) is a skin irritant that is used in "chemical peels" intended to remove the top layer of dead skin from the face and ultimately improve the complexion.
A single cell has a radius of 15 um, a volume of 14.1 picoliter, and a mass of 15.5 nanograms. what is the density of this cell in g/mL
The delta H for the oxidation of S in the gas phase to SO3 is -204 kJ/mol and for the oxidation of SO2 to SO3 is 89.5 kJ/mol. Find the enthalpy of formation of SO2 under these conditions.
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