Calculating the change in concentration after a whole number o... The rate at which a certain drug is eliminated by the body follows first-order kinetics, with a half life of 32 minutes. Suppose in a particular patient the concentration of this drug in the bloodstream immediately after injection is 1.6 ug/mL. What will the concentration be 160 minutes later? Round your answer to 2 significant digits.

Calculating the change in concentration after a whole number o... The rate at which a certain drug is eliminated by the body follows first-order kinetics, with a half life of 32 minutes. Suppose in a particular patient the concentration of this drug in the bloodstream immediately after injection is 1.6 ug/mL. What will the concentration be 160 minutes later? Round your answer to 2 significant digits.

Chemistry: Principles and Reactions

8th Edition

ISBN:9781305079373

Author:William L. Masterton, Cecile N. Hurley

Publisher:William L. Masterton, Cecile N. Hurley

Chapter11: Rate Of Reaction

Section: Chapter Questions

Problem 87QAP: A drug decomposes in the blood by a first-order process. A pill containing 0.500 g of the active...

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In a first-order reaction, suppose that a quantity X of a reactant is added at regular intervals of time, t. At first the amount of reactant in the system builds up; eventually, however, it levels off at a saturation value given by the expression a saturation value saturationvalue= x110a where a=0.30tt1/2 This analysis applies to prescription drugs, of which you take a certain amount each day. Suppose that you take 0.100 g of a drug three times a day and that the half-life for elimination is 2.0 days. Using this equation, calculate the mass of the drug in the body at saturation. Suppose further that side effects show up when 0.500 g of the drug accumulates in the body. As a pharmacist, what is the maximum dosage you could assign to a patient for an 8-h period without causing side effects?
The color change accompanying the reaction of phenolphthalein with strong base is illustrated below. The change in concentration of the dye can be followed by spectrophotometry (Section 4.9), and some data collected by that approach are given below. The initial concentrations were [phenolphthalein] = 0.0050 mol/L and [OH] = 0.61 mol/L. (Data are taken from review materials for kinetics at chemed.chem.purdue.edu.) (For more details on this reaction see L Nicholson, Journal of Chemical Education, Vol. 66, p. 725, 1989.) (a) Plot the data above as [phenolphthalein] versus time, and determine the average rate from t = 0 to t = 15 seconds and from t = 100 seconds to t = 125 seconds. Does the rate change? If so, why? (b) Use a graphical method to determine the order of the reaction with respect to phenolphthalein. Write the rate law, and determine the rate constant. (c) What is the half-life for the reaction?
A drug decomposes in the blood by a first-order process. A pill containing 0.500 g of the active ingredient reaches its maximum concentration of 2.5 mg/ 100 mL of blood. If the half-life of the active ingredient is 75 min, what is its concentration in the blood 2.0 h after the maximum concentration has been reached?
The uncoiling of deoxyribonucleic acid (DNA) is a first-order reaction. Its activation energy is 420 kJ. At 37C, the rate constant is 4.90104min1 (a) What is the half-life of the uncoiling at 37C (normal body temperature)? (b) What is the half-life of the uncoiling if the organism has a temperature of 40C(104F)? (c) By what factor does the rate of uncoiling increase (per C) over this temperature interval?
One can also define a third-life, t1/3, which is the amount of time necessary for one-third of an original amount of reactant to react. a For which order of kinetics is the third-life a constant? b Derive an expression for the t1/3 of a zeroth-order reaction. For how many third-lives will the reaction proceed before completion?
11.41 For a drug to be effective in treating an illness, its levels in the bloodstream must be maintained for a period of time. One way to measure the level of a drug in the body is to measure its rate of appearance in the urine. The rate of excretion of penicillin is first order, with a half-life of about 30 min. If a person receives an injection of 25 mg of penicillin at t = 0, how much penicillin remains in the body after 3 hours?
Consider a reaction of the type aA products, in which the rate law is found to he rate = k[A]3 (termolecular reactions are improbable but possible). If the first half-tife of the reaction is found to he 40. s, what is the time for the second half-life? Hint: Using your calculus knowledge, derive the integrated rate law from the differential rate law for a tennolecular reaction: Rate=d[A]dt=k[A]3
The acid-catalyzed iodination of acetone CH3COCH3(aq) + I2(aq) CH3COCH2I(aq) + HI(aq) is a common laboratory experiment used in general chemistry courses to teach the method of initial rates. The reaction is followed spectrophotometrically by the disappearance of the color of iodine in the solution. The following data (J. P. Birk and D. L Walters, Journal of Chemical Education, Vol. 69, p. 585, 1992) were collected at 23 C for this reaction. Determine the rate law for this reaction.
The hydrolysis of the sugar sucrose to the sugars glucose and fructose, C12H22O11+H2OC6H12O6+C6H12O6 follows a first-order rate equation for the disappearance of sucrose: Rate =k[C12H22O11] (The products of the reaction, glucose and fructose, have the same molecular formulas but differ in the arrangement of the atoms in their molecules.) (a) In neutral solution, k=2.11011s1 at 27 C and 8.51011s1 at 37 C. Determine the activation energy, the frequency factor, and the rate constant for this equation at 47 C (assuming the kinetics remain consistent with the Arrhenius equation at this temperature). (b) When a solution of sucrose with an initial concentration of 0.150 M reaches equilibrium, the concentration of sucrose is 1.65107M . How long will it take the solution to reach equilibrium at 27 C in the absence of a catalyst? Because the concentration of sucrose at equilibrium is so low, assume that the reaction is irreversible. (c) Why does assuming that the reaction is irreversible simplify the calculation in pan (b)?
Nitroglycerine is an extremely sensitive explosive. In a series of carefully controlled experiments, samples of the explosive were heated to 160 C and their first-order decomposition studied. Determine the average rate constants for each experiment using the following data: Initial [C3H5N3O9] (M) 4.88 3.52 2.29 1.81 5.33 4.05 2.95 1.72 t (s) 300 300 300 300 180 180 180 180 %Decomposed 52.0 52.9 53.2 53.9 34.6 35.9 36.0 35.4