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I II III I and III II and III

Suppose a reaction A + B {image} C occurs at some initial rate at 0°C. Which response includes all of the changes below that could decrease the rate of this reaction? I. lowering the temperature II. adding a catalyst III. decreasing the initial concentration of A. I II III I and III

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I II III I and III II and III

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  1. Suppose a reaction A + B {image} C occurs at some initial rate at 0°C. Which response includes all of the changes below that could decrease the rate of this reaction? I. lowering the temperature II. adding a catalyst III. decreasing the initial concentration of A • I • II • III • I and III • II and III

  2. What can be said about the stoichiometric coefficients of a balanced chemical equation for a reaction and the powers to which the concentrations are raised in the rate law expression? • There is an exact relationship between the two. • Not much can be said except that there is no necessary relationship. • The powers can be equal to the number of molecules that are formed. • The powers are equal to the number of molecules that must collide and react in the fastest step. • The powers equal the coefficients of the equation for the reaction at 298 K.

  3. The rate expression for the following reaction is found to be: rate = k[N2O5]. What is the overall reaction order? 2N2O5(g) {image} 4NO2(g) + O2(g) • first • second • third • fourth • none of these

  4. The units of the rate constant for a first order reaction could be _________. • M-1· min-1 • M • M ·min-1 • min-1 • M2· min-1

  5. A reaction is first order in X and second order in Y. Tripling the initial concentration of X and cutting the initial concentration of Y to three-fourths of its previous concentration at constant temperature causes the initial rate to _________ by a factor of _________. • increase, 1.69 • decrease, 0.19 • increase, 1.33 • decrease, 1.25 • increase, 2.25

  6. The following rate data apply to the reaction 3X + Y + 2Z {image} Products at a particular temperature. The form of the rate law expression is rate = ____________ . Experiment / Initial [X] / Initial [Y] / Initial [Z] / Initial Rate of Loss of X 1. 0.300 M / 0.200 M / 0.100 M / 6.40 x 10-3 M•min-1 2. 0.300 / 0.300 / 0.250 / 4.00 x 10-2 3. 0.600 / 0.300 / 0.250 / 4.00 x 10-2 4. 0.900 / 0.200 / 0.400 / 1.02 x 10-1 5. 0.800 / 0.400 / 0.100 / 6.40 x 10-3 • k[X][Y][Z] • k[X]3[Y][Z]2 • k[X]2[Z] • k[X][Y]2 • k[Z]2

  7. The oxidation of NO by O3 is first order in each of the reactants, and its rate constant is 1.5 x 107 M-1 ·s-1. If the concentration of NO is 1.0 x 10-7 M and the concentration of O3 is 2.0 x 10-7 M , what is the rate of reduction of O3 in M · s-1? • 3.0 x 10-6 • 2.5 x 10-14 • 7.5 x 10-7 • 3.0 x 106 • 3.0 x 10-7

  8. The gas phase reaction 3C + 2D {image} E + F obeys the rate-law expression rate = k[D] and has a half-life of 0.860 s. If 2.00 mole of D is injected into a 1.00-L container with excess C, what concentration of D remains after 1.50 seconds? • 0.48 M • 0.60 M • 1.68 M • 1.40 M • 1.06 M

  9. Given the following potential energy diagram for the one-step reaction X + Y {image} Z + R The reaction ___________. {image} • releases energy • absorbs energy • is impossible • occurs without a net change in energy • may either absorb or release energy

  10. The reaction A + B {image} C + D, obeys the rate law expression rate =k[A][B]. Which response lists all the proposed mechanisms below that are consistent with this information and none that are inconsistent? I. A + B {image} C + D one step II. A + B {image} E fast, equilibrium E {image} C + D slow III. A + B {image} E fast, equilibrium A + E {image} C + B slow • I and II • II • III • II and III • I, II, and III

  11. The principal reason for the increase in reaction rate with increasing temperature is • molecules collide more frequently at high temperatures. • the pressure exerted by reactant molecules increases with increasing temperature. • the activation energy increases with increasing temperature. • the fraction of high energy molecules increases with increasing temperature. • the activation energy for the forward reaction decreases while the activation energy for the reverse reaction increases.

  12. What would be the activation energy of a reaction if its rate constant at 35°C was double the value of its rate constant at 25°C? • 63.8 kJ/mol • 75.1 kJ/mol • 8.12 kJ/mol • 52.9 kJ/mol • 68.3 J/mol

  13. Which response includes all the true statements and no false statements? A catalyst can ___________ I. make a nonspontaneous reaction spontaneous II. speed up a forward reaction and slow down the reverse reaction III. lower the activation energy of the forward reaction IV. lower the activation energy of the reverse reaction • I and III • II and III • I and IV • III and IV • another one or another combination

  14. Which statement concerning enzymes is true? • Enzyme catalyze first-order reactions the only. • Enzyme catalyze second-order reactions the only. • Each enzyme catalyzes many different reactions in a living system. • Enzymes are proteins that act as catalysts for specific biochemical reactions. • Nitrogenase is as effective catalyst as iron in production of NH3.

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