1 / 14

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

rganz
Télécharger la présentation

I II III I and III II and III

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  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.

More Related