CHEM 1212 Exam 2 Practice Exam questions and answer (Chapters 13 and 14) updated 2020 solution - €13,75   In winkelwagen

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CHEM 1212 Exam 2 Practice Exam questions and answer (Chapters 13 and 14) updated 2020 solution

CHEM 1212 Exam 2 Practice Exam questions and answer (Chapters 13 and 14) updated 2020 solution 1) A reaction A B → C obeys the following rate law: Rate = k [B]2 If [A] is doubled, how will the rate change? 2) One difference between first and second order reaction is that 3) The decomposition of N2O5 in solution in carbon tetrachloride proceeds via the reaction 2N2O5 (aq) → 4NO2 (aq) O2 (aq) The reaction is first order and has a rate constant of x 10-3 s-1 at 64 °C. The rate law for the reaction is rate = _ 4) Consider the reaction: 8A(g) 5B(g) → 8C(g) 6D(g) If the rate of formation of [C] is mol/L∙s, at what rate is [B] consumed 5) What is the mass percentage of fluorine in a solution contain 0.075 mol F2 in 234 g of CF4? 6) Calculate the molality when 17.64g of C6H5OH is dissolved in 312g of benzene (C6H6) 7) The rate law of a reaction is rate = k[D][X]. The units of the rate constant are . 8) When determining the half-life of a first-order reaction, the half life does not depend on: 9) Calculate the numbers of moles of solute present in 274mL of 0.87M HCl solution. 10) Orange juice contains 236mg of C6H8O6 per kilogram of water. What is the concentration of C6H8O6 in ppb? 11) A solution is formed by dissolving 6.3 g glucose, C6H12O6, in 1 L of water. The vapor pressure of pure water is 23.8 torr. What is the vapor pressure of this solution? a) 22.82 torr b) 23.40 torr c) 23.78 torr d) 24.00 torr e) 23.12 torr 12) What is the osmotic pressure formed by dissolving 52.7g of C6H8O6 in 457mL of water at 25 °C? a) 13.8 atm b) 16.1atm c) 15.7 atm d) 16.8atm e) 14.0 atm 13) A solution of 0.43 m glucose in ethanol is created. What is the change in boiling point temperature? Kb of ethanol = 1.22 °C/m a) 0.83 °C b) 0.05 °C c) 0.52 °C d) 0.74 °C e) 1.12 °C SHORT ANSWER SECTION -#14 and #18 WILL NOT BE ON EXAM 2!! 14) The following mechanism has been proposed for the gas-phase reaction of H2 with ICl: H2 (g) ICl (g) → HI (g) HCl (g) HI (g) ICl (g) → I2 (g) HCl (g) a) Write the balanced equation for the overall reaction. H2 (g) 2I(g) → I2(g) 2HCl (g) b) Identify any intermediates in the mechanism. HI c) If the first step is slow and the second one is fast, which rate law do you expect to be observed for the overall reaction First one – Rate = k[H2][ICl] 15) The first-order rate constant for the decomposition of N2O5, 2 N2O5 (g) → 4 NO2 (g) O2 (g), at 70 °C is 6.82 × 10-3 s-1. Suppose we start with 0.0250 mol of N2O5 (g) in a volume of 2.0 L. a) How many moles of N2O5 will remain after 5.0 min? 0.0032 moles b) How many minutes will it take for the quantity of N2O5 to drop to 0.010 mol? 2.24 minutes c) What is the half-life of N2O5 at 70 °C? 101.6 seconds 16) A solution is made containing 43 g of phenol (C6H5OH) in 712 g of ethanol (CH3CH2OH). Calculate a) the mole fraction of C6H5OH 0.029 b) the mass percent of C6H5OH 5.69% c) the molality of C6H5OH 0.642m 17) The following data were measured for the reaction BF3 (g) NH3 (g) → F3BNH3 (g): Experiment [BF3] (M) [NH3] (M) Initial Rate (M/s) 1 0.250 0.250 0.2130 2 0.250 0.125 0.1065 3 0.200 0.100 0.0682 4 0.350 0.100 0.1193 5 0.175 0.100 0.0596 a) What is the rate law for the reaction? You will need to show calculations – it is not written directly from the given reaction Rate = k[BF3][NH3] b) What is the overall order of the reaction? 2nd c) Calculate the rate constant with proper units. k=3.41 M-1s-1 d) What is the rate when [BF3] = 0.100 M and [NH3] = 0.500 M? 0.1705 M/s 18) Understanding the high-temperature behavior of nitrogen oxides is essential for controlling pollution generated in automobile engines. The decomposition of nitric oxide (NO) to N2 and O2 is second order with a rate constant of 0.0796 M-1s-1 at 737 °C and 0.0815 M-1s-1 at 947 °C. Calculate the activation energy for the reaction. THIS PROBLEM WILL NOT BE ON EXAM 2 Ea = 1.15 kJ/ mol 19) Using the table below, calculate the freezing and boiling points of each of the following solutions: Solvent Normal Boiling Point (°C) Kb (°C/m) Normal Freezing Point (°C) Kf (°C/m) Water, H2O 100.0 0.51 0.0 1.86 Benzene, C6H6 80.1 2.53 5.5 5.12 Ethanol, C2H5OH 78.4 1.22 -114.6 1.99 Carbon tetrachloride, CCl4 76.8 5.02 -22.3 29.8 Choloroform, CHCl3 61.2 3.63 -63.5 4.68 a) 0.72 m sucrose in ethanol Boiling: 79.3 °C Freezing: -116.0 °C b) 13.2 g of decane, C10H22, in 50.0 g CHCl3 Boiling: 67.9 °C Freezing: -72.2 °C c) 2.50 g NaOH in 310 g of water Boiling: 101.5°C Freezing: -0.747 °C 20) The decomposition of a chemical warfare agent decomposes by a first-order reaction. It is found that the concentration of PCl5 is 0.0384M in the beginning and decomposed to 0.0150 M after 400 seconds. Determine the rate constant. k=0.0023 s-1

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