The enzyme urease catalyzez the reaction of urea,( NH2CONH2), with water to produce carbon dioxide and ammonia. In water,without the enzyme, the reaction proceeds with a first-order rate constant of 4.15*10-5S-1 at 100 °C. in the presence of the enzyme in water, the reaction proceeds with a rate constant of 3.4*104 s-1 at 21 °C. (a) write out the balanced equation for the reaction catalyzed by urease. (b) if the rate of the catalyzed and uncatalyzed reactions? (c) in actuality,what would you expect for the rate of the catalyzed reaction at 100 C as compared to that at 21 °C? (d) on the basis of parts (c) and (d), what can you conclude about the difference in activation energies for the catalyzed and uncatalyzed reactions?
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Chapter 14 Solutions
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- The decomposition of azomethane, (CH3)2N2, to nitrogen and ethane gases is a first-order reaction, (CH3)2N2(g)N2(g)+C2H6(g). At a certain temperature, a 29-mg sample of azomethane is reduced to 12 mg in 1.4 s. (a) What is the rate constant k for the decomposition at that temperature? (b) What is the half-life of the decomposition? (c) How long will it take to decompose 78% of the azomethane?arrow_forwardSucrose, a sugar, decomposes in acid solution to give glucose and fructose. The reaction is first-order in sucrose, and the rate constant at 25 C is k = 0.21 h1. If the initial concentration of sucrose is 0.010 mol/L, what is its concentration after 5.0 h?arrow_forwardThe 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)?arrow_forward
- For the past 10 years, the unsaturated hydrocarbon 1, 3-butadiene (CH2 = CH - CH = CH2) has ranked 38th among the top 50 industrial Chemicals. It is used primarily for the manufacture of synthetic rubber. An isomer exists also as cyclobutene: The isomerization of cyclobutene to butadiene is first-order and the rate constant has been measured as 2.0104s1 at 150 C in a 0.53-L ?ask. Determine the partial pressure of cyclobutene and its concentration after 30.0 minutes if an isomerization reaction is carried out at 150 C with an initial pressure of 55 torr.arrow_forwardOne possible mechanism for the decomposition of nitryl chloride, NO2CI, is What is the overall reaction? What rate law would be derived from this mechanism? What effect does increasing the concentration of the product NO2 have on the reaction rate?arrow_forwardThe Raschig reaction produces the industrially important reducing agent hydrazine, N2H4, from ammonia, NH3, and hypochlorite ion, OCl−, in basic aqueous solution. A proposed mechanism is Step 1: Step 2: Step 3: What is the overall stoichiometric equation? Which step is rate-limiting? What reaction intermediates are involved? What rate law is predicted by this mechanism?arrow_forward
- 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?arrow_forwardWhen enzymes are present at very low concentration, their effect on reaction rate can be described by first-order kinetics. Calculate by what factor the rate of an enzyme-catalyzed reaction changes when the enzyme concentration is changed from 1.5 107 M to 4.5 106 M.arrow_forwardThe initial concentration of the reactant in a tirst-order reaction A —» products is 0.64 rnol/L and the half-life is 30.0 s. Calculate the concentration of the reactant exactly 60 s after initiation of the reaction. How long would it take for the concentration of the reactant to drop to one-eighth its initial value? How long would it take for the concentration of the reactant to drop to 0.040 mol/L?arrow_forward
- The following rate constants were obtained in an experiment in which the decomposition of gaseous N2O; was studied as a function of temperature. The products were NO, and NO,. Temperature (K) 3.5 x 10_i 298 2.2 x 10"4 308 6.8 X IO-4 318 3.1 x 10 1 328 Determine Etfor this reaction in kj/mol.arrow_forwardThe decomposition of iodoethane in the gas phase proceeds according to the following equation: C2H5I(g)C2H4(g)+HI(g) At 660. K, k = 7.2 104 sl; at 720. K, k = 1.7 102 sl. What is the value of the rate constant for this first-order decomposition at 325C? If the initial pressure of iodoethane is 894 torr at 245C, what is the pressure of iodoethane after three half-lives?arrow_forwardThe 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.arrow_forward
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