Chem 106,Clicker Questions Which of the statements concerning relative rates of reaction is correct for the decomposition of dinitrogen pentoxide?   2 N2O5(g) ® 4 NO2(g) + O2(g) The rate of disappearance of N2O5 is 1/2 the rate of appearance of O2. The rate of appearance of NO2 is 1/4 the rate of appearance of O2. The rate of disappearance of N2O5 is 1/2 the rate of appearance of NO2. The rate of appearance of NO2 equals the rate of appearance of O2. The rate of disappearance of N2O5 equals the rate of appearance of NO2. Copyright 2006, David R. Anderson

Chem 106,Clicker Questions Which of the following relationships are correct for the reaction of peroxydisulfate ion with iodide ion?   S2O82-(aq) + 3 I-(aq) ® 2 SO42-(aq) + I3-(aq) Copyright 2006, David R. Anderson

Chem 106,Clicker Questions Ammonia can be formed by reacting nitrogen and hydrogen gases.   N2(g) + 3 H2(g) ® 2 NH3(g) If the rate of disappearance of hydrogen is 2.7  10-2 M/s, what is the rate of formation of ammonia? 1.8  10-2 M/s 2.7  10-2 M/s 4.0  10-2 M/s 5.4  10-2 M/s 8.1  10-2 M/s Copyright 2006, David R. Anderson

Chem 106,Clicker Questions Given the initial rate data for the reaction A + B ® C, determine the rate law for the reaction. rate = k[A] rate = k[B]2 rate = k[A][B] rate = k[A][B]2 rate = k[A]2[B] Copyright 2006, David R. Anderson

Chem 106,Clicker Questions Given the initial rate data for the reaction A + B ® C, determine the rate law for the reaction. rate = k[A] rate = k[B] rate = k[A][B] rate = k[A][B]2 rate = k[A]2[B] Copyright 2006, David R. Anderson

Chem 106,Clicker Questions Nitrogen dioxide reacts with ozone at a measurable rate at 231 K according to the equation below.   2 NO2(g) + O3(g) ® N2O5(g) + O2(g) What is overall order of the reaction? first-order second-order third-order fifth-order not enough information given to solve Copyright 2006, David R. Anderson

Chem 106,Clicker Questions The half-life of a first-order decomposition reaction is 188 seconds. If the initial concentration of reactant is 0.524 M, what is the concentration of reactant after 752 seconds? 0.0164 M 0.0328 M 0.0665 M 0.133 M 0.266 M Copyright 2006, David R. Anderson

Chem 106,Clicker Questions In general, as the temperature increases, the rate of a chemical reaction decreases due to fewer collisions with proper molecular orientation. decreases for endothermic reactions. decreases for exothermic reactions. increases due a greater number of effective collisions. increases due to a lowering of activation energy. Copyright 2006, David R. Anderson

Chem 106,Clicker Questions For a chemical reaction, the activation energy for the forward reaction is +215 kJ and the activation energy for the reverse reaction is +59 kJ. What is the overall energy change for the forward reaction? -274 kJ -156 kJ +156 kJ +215 kJ +274 kJ Copyright 2006, David R. Anderson

Chem 106,Clicker Questions In basic solution, (CH3)3CCl reacts according to the equation below.   (CH3)3CCl + OH- ® (CH3)3COH + Cl- The accepted mechanism for the reaction is (CH3)3CCl ® (CH3)3C+ + Cl- (slow) (CH3)3C+ + OH- ® (CH3)3COH (fast) What is the predicted rate law based on this mechanism? rate = k[(CH3)3CCl] rate = k[(CH3)3CCl]2 rate = k[(CH3)3C+][OH-] rate = k[(CH3)3CCl][OH-] rate = k[(CH3)3CCl][Cl-][OH-] Copyright 2006, David R. Anderson

Chem 106,Clicker Questions Nitrogen monoxide reacts with oxygen to produce nitrogen dioxide.   2 NO(g) + O2(g) ® 2 NO2(g) A proposed mechanism for this reaction is NO(g) + O2(g) NO3(g) (fast, equilibrium) NO(g) + NO3(g) ® 2 NO2(g) (slow) What is a rate law that is consistent with this mechanism? rate = k[NO][O2] rate = k[NO]2 rate = k[NO3][O2] rate = k[NO][O2]2 rate = k[NO]2[O2] Copyright 2006, David R. Anderson

Chem 106,Clicker Questions The effect of a catalyst is to lower the activation energy of a reaction. increase the energy of the products. increase the energy of the reactants. increase the number of collisions between reactants. decrease the change in enthalpy of a reaction. Copyright 2006, David R. Anderson

Chem 106,Clicker Questions Which of the following factors can affect the value of the rate constant of a chemical reaction?   1. changes in the concentrations of reactants 2. changes in the temperature of the system 3. the addition of a catalyst 1 only 2 only 3 only 2 and 3 1, 2, and 3 Copyright 2006, David R. Anderson

Answers c e a d b