Clicker Questions CHEM 120 Bethel 2020 EXAM 1 1 The concentration of acetic acid MM 60 05 g mol in vinegar is 5 0 by mass the rest can be assumed to be water What is the molality a 0 83 m b 0 88 m c 5 2 m d 0 083 m e 5 0 m 2 Calculate the Solubility of O2 in 25 0 C water at a partial pressure of 120 torr given that kn 1 3 x 10 3mol L atm for O2 at 25 0 C a 2 05 x 10 4 M b 2 1 x 10 4 M c 0 16 M d 0 156 M e 3 9 M 3 The osmotic pressure of an aqueous solution of Cobalt II Bromide is found to be 0 674 atm at 75 C Calculate the concentration of the salt a 0 0275 M b 0 00915 M c 0 00783 M d 0 0236 M e 0 0100 M 4 A solution is prepared by dissolving 0 131 g of a molecular substance in 25 4 g of water kFP 1 86 C If the solution has a freezing point of 0 104 C What is the molecular mass of the substance a 131 g mol b 251 g mol c 3 12 g mol d 92 1 g mol e 53 2 g mol 5 What is the rate law for the following reaction BrO3 aq 5Br aq 6H aq 3Br2 aq 3H2O aq Note that this reaction is first order in both BrO3 and Br and fourth order overall a Rate k BrO3 Br H b Rate k BrO3 Br H 2 c Rate k BrO3 Br 5 H 6 d Rate k BrO3 Br e Rate k BrO3 Br H 4 6 Rate data were obtained at 25 C for the following reaction What is the rate law expression for this reaction A 2B C 2D Experiment Initial A M Initial B M 1 2 3 4 0 10 0 30 0 10 0 20 0 10 0 30 0 30 0 40 Rate of C M s 3 0 x 10 4 9 0 x 10 4 3 0 x 10 4 6 0 x 10 4 a Rate k A B b Rate k A B 2 c Rate k A 2 B d Rate k A e Rate k B 7 The rate of decomposition of chemical P was measured and a linear fit was for for ln P vs t The best fit line has the equation y 0 0217x 6 2146 What is the rate law a Rate 0 0217 P b Rate 0 0217 P 2 c Rate 0 0217 d Rate 0 0217 P e Rate 0 0217 P 2 8 Sucrose decomposes to form fructose and glucose in an acidic solution with the following rate law Rate k C12H22O11 and k 0 216 hr 1 at 25 0 c What is the amount of time required for an initial concentration of 0 449M to decompose to 0 0561 a 0 216 hours b 0 648 hours c 3 21 hours d 4 61hours e 9 63 hours 9 The rate law of a reaction is Rate k NOBr 2 If the half life for this reaction is 2 00 s when NOBr 0 0 900 M How long will it take to decrease the concentration of NOBR to 0 010 M a 0 35 s b 0 56 s c 4 0 s d 13 s e 180 s 10 Dinitrogen Tetroxide decomposes to nitrogen dioxide and the following rate constants were determined at varying temperatures k1 4 5 x 103 s 1 T1 25 0 C k2 1 5 x 104 s 1 T1 25 0 C What is the activation energy a 2 00 x 10 4 kJ mol b 0 751 kJ mol c 20 8 kJ mol d 7 51 x 102 kJ mol e 2 08 x 10 4 kJ mol 11 A reaction generates Hydrazine from Ammonia and Hypochlorate according to the following proposed mechanisms Step 1 Fast NH3 aq OCl aq NH2Cl aq OH aq Step 2 Slow NH2Cl aq NH3 aq N2H5 aq Cl aq Step 3 Fast N2H5 aq OH aq N2H4 aq H2O aq Which of the following is TRUE a The overall reaction is NH3 aq OCl aq N2H4 aq Cl aq b Step 1 is rate determining c The rate equation for step 2 is Rate k2 NH3 2 Cl d NH2Cl is a reaction intermediate e H2O is a reaction intermediate 12 What is the mole fraction of NaCl in an aqueous solution density 1 20 g mol that is 2 5 molal Sodium Chloride MM 58 44 g mol a 0 15 b 2 6 c 2 3 d 0 045 e 0 043 13 What does this graph indicate a Zero order rate law b First order rate law c Second order rate law d Activation energy e None of the above Answer key B B C D B D A E C D E A B EXAM 2 1 For the reaction 2NO2 g N2O4 g If the equilibrium concentrations are NO2 1 50 M and N2O4 10 7 M what is the equilibrium constant a 4 76 b 0 210 c 0 140 d 7 13 e 16 1 2 Kp for the decomposition of nitrogen dioxide gas into nitrogen monoxide and oxygen gas is 6 3 x 10 13 at 25 C What is Kc Hint remember the first step is always a balanced chemical equation 3 4 5 6 7 a 1 6 x 10 9 b 6 3 x 10 13 c 1 5 x 10 11 d 2 6 x 10 14 e 2 5 x 10 16 PCl3 g Cl2 g PCl5 g K 33 250 0 C If an experiment has starting concentrations of 0 050 M PCl3 and 0 050 M Cl2 what is the concentration of Cl2 after the reaction has reached equilibrium a 0 043 M b 0 023 M c 0 027 M d 0 037 M e 0 107 M NO g is produced during combustion at high temperature according to the reaction N2 g O2 g 2NO g K 1 0 x 10 5 at 1500 K If a sample of air has a concentration of 0 080 M N2 and 0 020 M O2 what is the concentration of NO after combustion at 1500 K a 0 080 M b 0 020 M c 1 6 x 10 6 M d 6 3 x 10 5 M e 1 3 x 10 4 M Th water gas shift reaction is used to produce H2 industrially CO g H2O g CO2 g H2 g Which of the following conditions will result in the largest increase of the production of hydrogen gas a Increasing concentration of CO g and CO2 g b Decreasing concentration of H2O g and CO2 g c Decreasing concentration of H2O g and CO g d Increasing concentration of H2O g and CO g e Increasing concentration CO2 g Which …