Study Guide_Exam 1

Study Guide_Exam 1 - STUDY GUIDE Chapter 4 Review 1. How...

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Unformatted text preview: STUDY GUIDE Chapter 4 Review 1. How many Fe atoms and how many moles of Fe atoms are in 500.0 g of iron? 5.39E24 atoms Fe 2. Aluminum metal is produced by passing an electric current through a solution of aluminum oxide (Al2O3) dissolved in molten cryolite (Na3AlF6). Calculate the molar masses of Al2O3 and Na3AlF6. Al2O3 = 101. 96 g/mol and Na3AlF6= 209.95 g/mol 3. Calculate the molar mass of Ca3(PO4)2. a. How many moles are present in 1.00 g of the compound? 3.22E-3 mol b. How many grams are present in 5.00 mol of the compound? 1.55E3 g c. How many grams of phosphorous are present in 5.00 mol of the compound? 310 g 4. Fungal laccase, a blue protein found in wood-rotting fungi, is 0.390% Cu by mass. If a fungal laccase molecule contains 4 copper atoms, what is the molar mass of fungal laccase? 6.54E4 g/mol 5. Balance the eguations: a. b. c. Cu(s) + Zn(s) + Au2S3(s) + 2AgNO3(aq) 2HCl(aq) 3 H2(g) → → 2Ag(s) + ZnCl2(aq) + 2 Au(s) + Cu(NO3)2(aq) H2(g) → 3H2S(g) 6. Aspirin (C9H8O4) is synthesized by reacting salicylic acid (C7H6O3) with acetic anhydride (C4H6O3). The balanced equation is C7H6O3 + C4H6O3 → C9H8O4 + HC2H3O2 a. What is the mass of the acetic anhydride is needed to completely consume 1.00 X 102 g salicylic acid? 73.9 g b. What is the maximum mass of aspirin (the theoretical yield) that could be produced in this reaction? 1.30E2 g 7. Consider the reaction: Mg(s) + I2(s) → MgI2(s) Identify the limiting reagent in each of the reaction mixtures below: a. 0.16 mol Mg and 0.25 mol I2 b. 0.14 mol Mg and 0.14 mol I2 Neither c. 6.078g Mg and 63.46 g I2 Neither d. 1.00 g Mg and 2.00g I2 8. Mercury and bromine will react with each other to produce mercury(II) bromide: Hg(l) + Br2(l) → HgBr2(s) a. What mass of HgBr2 can be produced from the reaction of 10.0g Hg and 9.00g Br2? 18 g What mass of which reagent is left unreacted? 1.03 g b. What mass of HgBr2 can be produced from the reaction of 5.00 ml mercury (density =13.6 g/ml) and 5.00 ml bromine (density =3.10 g/ml)? 35 g Chapter 15 Review 1. Distinguish among the initial rate- instantaneous rate at t=0 seconds, average rate= rate measured over time, and instantaneous rate= rate at a specific time of a chemical reaction. Which of the rates usually has the largest value? Initial rate 2. Define each: a. Elementary step- single step in a reaction mechanism. b. Reaction mechanism- series of elementary steps to give overall balanced equation c. Rate-determining step = slowest step in a reaction mechanism 3. For the reaction: 2H2(g) The observed rate law is Rate= k[NO]2[H2] Which of these changes would affect the value of the rate constant k? a. Increasing the partial pressure of hydrogen gas b. Changing the temperature + 2NO(g) → N2(g) + 2H2O(g) c. Using an appropriate catalyst 4. Consider the reaction 4PH3(g) → P4(g) + 6H2(g) If, in a certain experiment, over a specific time period, 0.0048 mol 4PH3 is consumed in a 2.0 L container each second of the reaction, what are the rates of production of P4 =6.0E-4 mol/L-s and H2 = 3.6E-3 mol/L-s in this experiment? 5. What are the units of each of the following if the concentrations are expressed in moles per liter and the time in seconds? a. Rate of a chemical reaction mol/L-s b. Rate constant for a zero order rate law mol/L-s c. Rate constant for a first order rate law 1/s d. Rate constant for a second order rate law L/mol-s 6. The rate law for the reaction Cl2(g) + CHCl3(g) → HCl(g) + CCl4(g) Rate= k [Cl2]1/2[CHCl3] What are the units for k, assuming time in seconds and concentrations in mol/L? L1/2/mol1/2-s 7. The reaction 2NO(g) + Cl2(g) → 2NOCL(g) Was studied at -10C. The following results were obtained where Rate= -∆[ Cl2] ∆t Initial Conc. NO 0.1 0.1 0.2 Initial Conc. Cl2 0.1 0.2 0.2 Initial rate 0.18 0.36 1.45 / a. What is the rate law? Rate= k [NO]2[Cl2] b. What is the value of the rate constant? K=180 L2/mol2-min 8. You have the following reaction 2ClO2(aq) + Where 2OH-(aq) → ClO3-(aq) + ClO2-(aq) + H2O(l) Rate = - ∆[ ClO2] ∆t / Initial Conc. ClO 0.05 0.1 0.1 Initial Conc. OH 0.1 0.1 0.05 Initial rate 5.75E­ 02 2.30E­ 01 1.15E­ 01 a. Determine the rate law and the value of the rate constant. Rate= k[ClO2]2[OH] b. What would be the initial rate for an experiment with [ClO2]o =0.175M and [OH]o=0.0844M? 0.594 mol/L-s 9. A general reaction aA → bB At a particular temperature and [A]o=2.8E10-3M, concentration versus time data were collected for this reaction, and a plot of 1/[A] versus time resulted in a straight line with a slope of 3.60E10-2 L/mol-s. a. Determine the rate law rate=k[A]2, the integrated rate law 1/[A] = kt + 1/[A]o, and the value of the rate constant for this reaction k=slope=3.6E-2 L/mol-s. b. Calculate the half-life for this reaction. 9.92E3 s c. How much time is required for the concentration of A to decrease to 7.00E-4 M? 2.98E4 s ...
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