CHM1046 EXAM 2 QUESTIONS WITH DETAILED CORRECT ANSWERS

Most of the H2 used in the Harber-Bosch process is produced by steam-reforming of methane followed by the water-gas shift reaction CO(g)+H2O(g) - - CO2(g)+H2(g) Kp= 10 at 400 degrees Celsius Suppose a reaction vessel at 400 degrees Celsius contains a mixture of CO, steam, and H2 at the concentrations shown in the ICE table shown below: A. Kp= (Pco2)(PH2)/(Pco)(PH2O) B. Kp= (Pco)(PH2O)/(PCO2)(PH2) C. Kp= (PCO2)(PH2)/(PCO) D. Kp= (PCO2)/(PCO)(PH2O) - correct answers Kp= (Pco2)(PH2)/(Pco)(PH2O) If you put the above values into the K equation, you end up with a polynomial that when plugged into the quadratic equations gives you two answers, x=2.96 and x=1.5. Which of the values would you use to calculate the equilibrium concentration? A. 2.96 B. 1.5 C. Neither D. Both would work - correct answers 1.5 Ignoring the Kp above but using the same concentrations of the reactants, for which Kp value below could you confidently ignore x in your calculations? A. Kp= 1000 B. Kp=10 C. Kp=0.1 D. Kp=0.001 - correct answers Kp=0.001 Which equilibrium reaction below shifts to the product side when the temperature is increased and to the reactant side when the volume is decreased (pressure increased) at constant temperature? A. N2(g) + 3H2(g) -- 2NH3(g) (DELTA H0) B. N2O2 (g) -- 2NO2(g) (DELTA H0) C. H2 (g) + I2(g) -- 2HI (g) (DELTA H0) D. PCL3(g)+Cl2(g)-- PCl5(g)(DELTAH0) - correct answers N2O2 (g) -- 2NO2(g) (DELTAH0) To the right is the reaction coordinate diagram for the conversion of N2O4 to 2NO2. What is the first step to the reaction? A. Can't tell without DELTA H B. Endothermic C. Exothermic D. Neither - correct answers Endothermic How many elementary steps are in this reaction? A. 6 B. 4 C. 3 D. 2 E. 1 - correct answers 3 Which of the following is an elementary step of this reaction? A. NO2+NO3-- 2NO2+O B. N2O4 + O -- O2N-NO3 C. N2O4-2NO2 D. N2O4 + O - NO2+NO3 E. Both A and D - correct answers N2O4 + O - NO2+NO3 How many transition states are there? A. 6 B. 4 C. 3 D. 2 E. 1 - correct answers 3 Using the following graph to the right, the student determines that a reaction is zero order. Unfortunately, they forgot to label the axes. What are the correct labels for the x and y axes? A. X axis= time, y axis = 1/[A] B. X axis = time, y axis = 1/ln[A] C. X axis = time, y axis = [A] D. X axis= time, y axis= ln[A] E. X axis = 1/time, y axis =1/[A] - correct answers X axis = time, y axis = [A] For the Equilibrium A - B, at a given temperature, supposed the rate of constant for the forward reaction is two times larger than the rate of constant for the reverse reaction. Is the value of the equilibrium constant: A. K1 B. K=1 C. K1 D. Can't be answered without concentrations - correct answers K1 Not only is carbon monoxide poisonous, but it can form toxic volatile compounds with metals like nickel as shown in the following reaction: Ni(CO)4 - Ni(s)+ 4CO(g) DELTAH= 161 kJ/mol and while this may sound like a bad reaction, this equilibrium is used industrially to purify nickel metal by the Mond process, named for the scientist who synthesized Ni(CO)4 in 1890 What is the equilibrium constant express (Law of mass action) for this reaction? A. K= [Ni][Co]4/[Ni(CO)4] B. K= [CO]4/[Ni(CO)4] C. K= [Ni(CO)4]/[CO]4 D. K= [Ni(CO)4]/[Ni][CO]4 - correct answers K= [CO]4/[Ni(CO)4] Which of the following could be used to increase the amount of CO(g) produced? I. Decreasing the number of concentration of Ni(s) II. Increasing the pressure by decreasing the volume III. Increasing the temperature IV. Increasing the amount of Ni(CO)4 (g) A. I and II only B. I and III only C. I,III, and IV only D. II and III only E. III and IV only - correct answers III and IV only Will increasing the pressure by adding CO2 to the above reaction chamber shift the reaction towards: A. Products B. Reactants C. It will not shift - correct answers It will not shift Which of the following changes will influence the equilibrium constant (K) for this reaction? A. Changing the volume of the chamber B. Adding a catalyst C. Adding an inert gas D. Removing CO E. None of the above - correct answers None of the above What are the units on k for the following rate laws: rate = k[A]3[B]2 A. S-1 B. M s-1 C. M-1 s-1 D. M-4 s-1 E. M-5 S-1 - correct answers M-4 s-1 The hemoglobin protein (Hb) can bind up to four oxygen atoms (O2) at a time which is important for transporting oxygen through your body. The equilibrium constants for these sequential binding events are given below: - Hb(aq)+O2(aq) - HbO2(aq) - HbO2(aq)+O2(aq) - Hb(O2)2 (aq)