8. A nuclear stress test utilizes a gamma-emitting radioisotope such as thallium-201 to follow the flow of blood through the heart. Th first-order rate constant for the decay of thallium-201 is 9.5 x 10 3 hr . Calculate how long it takes for a 0.50 M solution of thallium-201 to disintegrate to 0.15 M. DOLL F11 F9 F10

One experimental procedure that can be used to determine the rate law of a reaction is the method of initial rates. What data are gathered in the method of initial rates, and how are these data manipulated to determine k and the orders of the species in the rate law? Are the units for k. the rate constant, the same for all rate laws? Explain. If a reaction is first order in A, what happens to the rate if [A] is tripled? If the initial rate for a reaction increases by a factor of 16 when [A] is quadrupled, what is the order of n? If a reaction is third order in A and [A] is doubled, what happens to the initial rate? If a reaction is zero order, what effect does [A] have on the initial rate of a reaction?

An excellent way to make highly pure nickel metal for use in specialized steel alloys is to decompose Ni(CO)4 by heating it in a vacuum to slightly above room temperature. Ni(CO)4(g) Ni(s) + 4 CO(g) The reaction is proposed to occur in four steps, the first of which is Ni(CO)4(g) Ni(CO)3(g) + CO(g) Kinetic studies of this first-order decomposition reaction have been carried out between 47.3 C and 66.0 C to give the results in the table. (a) Determine the activation energy for this reaction. (b) Ni(CO)4 is formed by the reaction of nickel metal with carbon monoxide. Suppose that 2.05 g CO is combined with 0.125 g nickel metal. Determine the maximum mass (g) of Ni(CO)4 that can be formed. Replacement of CO by another molecule in Ni(CO)4 was studied in the nonaqueous solvents toluene and hexane to understand the general principles that govern the chemistry of such compounds. Ni(CO)4(g) + P(CH3)3 Ni(CO)3P(CH3)3 + CO A detailed study of the kinetics of the reaction led to the mechanism Step1:(slow)Ni(CO)4Ni(CO)3+COStep2:(fast)Ni(CO)3+P(CH3)3Ni(CO)3P(CH3)3 (c) Which step in the mechanism is unimolecular? Which is bimolecular? (d) Add the steps of the mechanism to show that the result is the balanced equation for the observed reaction. (e) Is there an intermediate in this reaction? If so, what is it? (f) It was found that doubling the concentration of Ni(CO)4 increased the reaction rate by a factor of 2. Doubling the concentration of P(CH3)3 had no effect on the reaction rate. Based on this information, write the rate equation for the reaction. (g) Does the experimental rate equation support the proposed mechanism? Why or why not?

Radioactive gold-198 is used in the diagnosis of liver problems. 198Au decays in a first-order process, emitting a particle (electron). The half-life of this isotope is 2.7 days. You begin with a 5.6-mg sample of the isotope. Calculate how much gold-198 remains after 1.0 day.