Download 16 Solved MCQs on General Chemistry II - Examination 2 | CHEM 010 and more Exams Chemistry in PDF only on Docsity! Version A Exam 2 Chem 10, Fall 2011 Multiple choice: 16 Problems; 6.25 points each. Please, provide answers on the scantron. Include exam version on the scantron! Name:__Answer Key Student ID:________________________ Lab TA/section:_______________________ 1 1. The equilibrium constant, Kp, for the reaction H2(g) + I2(g) 2HI(g) is 75.2 at 425C. A rigid cylinder at that temperature contains 0.127 atm of hydrogen, 0.134 atm of iodine, and 1.055 atm of hydrogen iodide. Is the system at equilibrium? A. No, the forward reaction must proceed to establish equilibrium. B. No, the reverse reaction must proceed to establish equilibrium. C. Need to know the volume of the container before deciding. D. Need to know the starting concentrations of all substances before deciding. Q = P2 (HI) /P(H2) P(I2) = 65.4; Q < Kp therefore reaction shifts to right (forward reaction) to reach equilibrium. 2. A buffer is to be prepared by adding solid sodium acetate to 0.10 M CH3COOH. Which of the following concentrations of sodium acetate will produce the most effective buffer? A. 0.30 M CH3COONa B. 2.5 M CH3COONa C. 2.0 M CH3COONa D. 1.5 M CH3COONa A buffer is most effective when [A-] = [HA]; then pH = pKa 3. Increasing the initial amount of the limiting reactant in a reaction will increase the value of the equilibrium constant, Kc. A. True B. False C. Not enough information to determine D. Need to know the specific concentrations to determine 4. The following reaction is at equilibrium in a sealed container. N2(g) + 3H2(g) 2NH3(g), Hrxn < 0 Which of the following actions will increase the value of the equilibrium constant, Kc? A. adding a catalyst B. adding more N2 C. lowering the temperature (exothermic reaction, heat is a product; equilibrium will shift to right with lowering the temperature; more product = higher Kc) D. None of these choices is correct. 2
