HONORS CHEMISTRY HARVARD-WESTLAKE SECOND SEMESTER FINAL EXAM REVIEW

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1 HONORS CHEMISTRY HARVARD-WESTLAKE SECOND SEMESTER FINAL EXAM REVIEW At the end of the semester, a 10th-grade chemistry teacher asked her students what was the most important thing that they learned in lab. A student promptly raised his hand and said, "Never lick the spoon." FINAL EXAM MATERIALS 1

2 FINAL EXAM MATERIALS 2

3 How are you going to prepare for the Final Exam? Final Exam Review The best preparation for the final exam is consistent study habits and effort throughout the year. We know that a lot of material has gone down the lab sink, so to speak, and so we also have some suggestions for areas you should concentrate on as you prepare. Pay close attention to the listing below. The items are given as things you should be able to do if you intend to do well on the exam. A brief description of the final exam format would be "business as usual, but more of it". The exam consists of 30 multiple choice questions, 4 major required problems, your choice of 4 out of 6 minor problems, and your choice of 1 out of 32 essays. The essays are somewhat more involved than usual. For the exam you will be provided with a periodic table, an electronegativity table, the Standard Reduction Potential table, the activity series, the solubility rules, values of R (the gas constant) and the value for F (the Faraday number) The exam is worth approximately 110 points. Following the listing of topics, you will find a "sample" exam. Most of the questions have been drawn from earlier work. The "exam" is intended for practice only and should not be used to gauge the specific content of the real thing. On the other hand, no attempt has been made to select problem areas which will not appear on the exam. The Topics Unit 1 -you should be familiar with the Rutherford experiment and the conclusions that it led to -you should be able to describe the number and type of each particle in a given atom or ion -you should be able to name binary and ternary compounds -you should be able to write chemical formulas from the names of binary and ternary compounds -you should be able to calculate molar mass (g/mol) -you should be able to change g to mol and mol to g -you should be able to do simple % composition calculations Unit 2 -you should be able to complete and balance and identify types of chemical reactions, including non-trivial redox Unit 3 -you should be able to do mass-mass stoichiometry -you should be able to calculate the Molarity of a given substance in solution Unit 4 -you should be able to identify some differences between classical atomic theory and quantum theory -you should be able to write correct electron configurations for elements up to Z = 70 -you should be able to compare major periodic properties for elements (size, ionization energy, etc.), and interpret their effects on chemical or physical properties of elements FINAL EXAM MATERIALS 3

4 Unit 5 -you should be able to use Hess' Law, either by adding chemical reactions or by using H f data, to determine the enthalpy change for a reaction -you should be able to identify exothermic and endothermic reactions and give appropriate reaction energy diagrams for each -you should be able to do stoichiometric calculations involving enthalpy changes -given enthalpy and entropy data, you should be able to determine which reactions in a group are likely to be more spontaneous -you should be able to determine the free energy change for a process given enthalpy and entropy data Unit 6 -you should be able to identify correct Lewis structures for atoms and simple molecules and ions -you should be able to distinguish between the major types of bonding: ionic and covalent -you should be able to determine the net polarity of a molecule from a diagram of its structure -you should be able to identify the type of hybridization of the central atom in a simple molecule or ion -you should be able to predict the presence of hydrogen bonding Unit 7 -you should be able to make qualitative judgments about the vapor pressure of a liquid -you should be able to solve simple partial pressure problems -you should be able to apply Boyle's or Charles' Laws to predict the pressure/volume behavior of a gas system -you should be able to apply the ideal gas law to solve problems, including stoichiometry Unit 8 -you should be able to calculate the molality of a given substance in solution -you should be able to find the freezing point of a solution -you should be able to determine the molar mass of an unknown substance from freezing point depression data Unit 9 -you should be able to write rate law expressions from initial rate and concentration data and evaluate the rate constant -you should be able to discuss aspects of collision theory -you should be able to complete a consistent mechanism for a simple reaction given the rate law and appropriate data Unit 10 -you should be able to write equilibrium constant expressions for reactions and evaluate them given appropriate data -you should be able to apply LeChâtelier's Principle in predicting the effect that changes will have on the state of a system at equilibrium, including the effects of catalysts -you should be able to express the solubility of a solid in water given its K sp (and the reverse) -you should be able to predict qualitatively and quantitatively whether a precipitate will form when ions are mixed FINAL EXAM MATERIALS 4

5 Unit 11 -you should be able to balance or complete nuclear reactions -you should be able to calculate the amount of an isotope that will remain after a specified period of time Unit 12 -you should know some of the properties of acids and bases -you should be able to use K a in calculations to determine ph and % dissociation of a weak acid solution -you should be able to distinguish among common strong/weak acids and bases -you should know how a buffer solution is prepared and how it functions (not to mention why) Unit 13 -you should be able to calculate E o for an electrochemical cell and correctly interpret a diagram for a galvanic cell (flow of electrons, anode, cathode, etc.) -you should be able to predict the products of the electrolysis of a dilute aqueous salt solution using inert electrodes -you should be able to apply Faraday's law to a problem involving plating or electrolysis in water solutions Sample Final Exam--Some typical multiple choice 1. The percent, by mass, of phosphorus in Ca 3 (PO 4 ) 2 is a. 10% b. 20% c. 30% d. 40% e. 50% That's all there is! 2. How many neutrons are in an atom of rubidium with a mass number of 87? a. 37 b. 74 c. 50 d. 87 e What product is expected at the cathode when a dilute solution of sodium chloride is electrolyzed using inert electrodes? a. Na b. Cl 2 c. O 2 d. H 2 4. Rutherford, Geiger and Marsden arrived at a model for the atom different from that of J. J. Thomson. In it a. electrons are surrounded by a dense mass of protons and neutrons b. neutrons are positioned between the protons electrons to keep them apart c. electrons orbit a very dense nucleus containing protons and neutrons d. the nucleus takes up much of the volume of the atom 5. When copper and zinc are placed in contact in a moist environment, which reaction is likely to occur? a. Cu 2+ + Zn Cu + Zn 2+ b. Zn + H 2 O ZnO + H 2 c. Cu + H 2 O CuO + H 2 d. Cu + Zn 2+ Cu 2+ + Zn 6. An atom of element X has the electron configuration 1s 2 2s 2 2p 6 3s 2 and element Y has the electron configuration 1s 2 2s 2 2p 6 3s 2 3p 5. The formula for a compound of these two elements is: a. X 2 Y b. XY c. XY 3 d. XY 2 e. X 12 Y The correct electron dot symbol for Ga is FINAL EXAM MATERIALS 5

6 8. As one moves down the periodic table, which of the following properties increases? a. electron affinity b. ionization energy c. electronegativity d. atomic radius For the following question, compare the assertion (top) and the reason (bottom) and select the appropriate answer from the options given below: a. both are true and reason fits the assertion b. both are true but reason does not explain assertion c. only the assertion is true d. only the reason is a true statement e. both are false 9. The first ionization energy of Li is less than that of Na BECAUSE Li is a smaller atom than Na. 10. The hybrid orbitals of the carbon atom in methane, CH 4, are called a. sp b. sp 2 c. sp 3 d. sp Of the following molecules, all of which have polar bonds, the non-polar molecule is a. HCl (linear) b. H 2 O (v-shaped) c. NH 3 (trigonal pyramid) d. CCl 4 (tetrahedron) 12. For which of the following transformations is hydrogen bonding expected to be the strongest force to overcome? a. boiling ICl b. melting CH 3 OH c. subliming CO 2 d. boiling ClO 2 e. melting I A liquid will boil when a. its vapor pressure is less than atmospheric pressure b. its critical pressure exceeds atmospheric pressure c. its critical temperature equals room temperature d. its vapor pressure equals atmospheric pressure e. its temperature reaches the triple point 14. A volume of 48 ml of hydrogen gas is collected when the pressure is 600 mm Hg (to the nearest mm). If all other conditions remain constant what volume will this gas occupy when the pressure becomes 800 mm Hg (also to the nearest mm)? a. less than 36 ml b. 36 ml c. 48 ml d. 64 ml 15. The volume occupied by 0.50 mole of propane gas, at a temperature of 27 o C and a pressure of kpa is best expressed by which of the following? a. (0.50 x 8.31 x 27)/202.6 b. (0.50 x 8.31 x 300)/202.6 c. (0.50 x 8.31 x 273)/300 d. (0.50 x 8.31 x 300)/(202.6 x 760) e. (0.50 x 8.31 x 27)/(202.6 x 760) 16. Given these two reaction heats: S(s) + O 2 (g) SO 2 (g) H = -297 kj S(s) + 3 / 2 O 2 (g) SO 3 (g) H = -438 kj What is the heat of reaction for 2 SO 2 (g) + O 2 (g) 2 SO 3 (g) under the same conditions? a kj b kj c kj d kj e kj FINAL EXAM MATERIALS 6

7 17. Consider the reaction below: 1.7 kj + NaCl(s) + H 2 O(l) Na + (aq) + Cl - (aq) Which of the following combinations for H and S is correct? a. +,- b. -,+ c. -,- d. +,+ 18. How many grams of sodium hydroxide pellets are required to prepare 50 ml (to the nearest 1 ml) of a 0.15 M solution? a b. 2.0 c. 3.0 d. 20 (to the nearest 1) 19. What is the freezing point of a 0.78 m water solution of non-volatile molecular solute? (K f = 1.86) a o C b o C c o C d o C e. insufficient information 20. A solution of a sodium salt that will form a precipitate with 0.1 M Pb(NO 3 ) 2 but NOT with 0.1 M Ba(NO 3 ) 2 is a. NaCl b. Na 2 CO 3 c. Na 2 SO 4 d. Na 3 PO 4 e. Na 2 SO The [H 3 O + ] of a solution is 2.3 x 10-4 M. The ph of the solution lies between a. 1 and 2 b. 2 and 3 c. 3 and 4 d. 4 and Which compound is a weak base? a. sodium hydroxide, NaOH b. potassium hydroxide, KOH c. aluminum hydroxide, Al(OH) 3 d. lithium hydroxide, LiOH 23. At the "end-point" of an acid-base titration, which of the following would always be true? a. the volume of acid equals the volume of base b. the solution is neutral (ph = 7) c. [H + ] = [OH - ] d. moles of H + added equals moles of OH - that were present e. none of the above 24. Which one of the following is not a property you would expect of an acid? a. reacts with magnesium to give H 2 b. tastes sour c. water solution conducts electricity d. feels slippery 25. When properly balanced with the smallest integer coefficients for acidic solution, the sum of all the coefficients in the half reaction below will be: CrO 3 Cr 3+ (H + ) a. 12 b. 14 c. 8 d. 5 e. none of these 26. What is the standard voltage, E o, for this electrochemical cell? Cr(s) + 3 Ag + (aq) Cr 3+ (aq) + 3 Ag(s) Half reaction Ag + (aq) + e - Ag(s) Cr 3+ (aq) + 3 e - Cr(s) E o V V a v b v c v d v FINAL EXAM MATERIALS 7

8 27. Consider these half-cell reactions: 2 AgO + H 2 O + 2 e - Ag 2 O + 2 OH - E o = V Zn(OH) e - Zn + 2 OH - E o = V A galvanic cell made from these half-cells: a. would have a cell potential of v b. would be in a state of equilibrium c. would consume zinc metal and produce Ag 2 O d. would have a cell potential of v e. would work only under acidic conditions 28. In an electrolysis cell, the passage of 6.02 x electrons can produce a Litres of H 2 gas (at STP) from water b Litres of O 2 gas (at STP) from water c. 1 mole of Cl 2 gas from HCl solution d. 1 mole of metallic silver from AgNO 3 solution e. 1 mole of metallic copper from CuSO 4 solution Po 4 2 He +? The missing product in the equation above is a Pb b. 82 Pb c. 82 Pb d. 84 Pb e. 82 Pb 30. The most massive particle among the following is a. alpha particle b. beta particle c. positron d. neutron Some typical required problems 31. When hydrochloric acid and zinc metal react, the gas produced is collected in an evacuated flask. After the system has returned to room temperature (27.2 o C), the pressure inside the flask is 350 mm Hg. The volume of the flask is 255 ml. The energy released during this reaction is kj per mole of Zn. a. How many moles of gas have been collected? b. Write the chemical reaction, including the correct numerical energy term on the appropriate side c. Assuming that the zinc has been completely consumed, how many grams of zinc were used in this reaction? d. If the resulting solution was evaporated, what is the name of the solid compound that would remain? e. How many kj of heat energy are released by the amounts used in this problem? 32. Given the following reactions: S(s) + O 2 (g) SO 2 (g) H o = -297 kj/mol SO 2 (g) O 2(g) SO 3 (g) H o = -141 kj/mol a. calculate H for the reaction: S(s) O 2(g) SO 3 (g) b. using values in your text book, calculate S o at 298 K for this reaction. c. using your value for H o and S o, calculate G o at 298 K. d. sketch a reaction energy diagram for the reaction, indicating where the enthalpy quantity would be measured. FINAL EXAM MATERIALS 8

9 33. The reaction NO 2 (g) + CO(g) NO(g) + CO 2 (g) has been studied to determine the effect of varying the concentrations of nitrogen dioxide and carbon monoxide upon the rate of the reaction. The rate was determined by noting changes in absorbance in the system (NO 2 is colored, all other gases are colorless). Rate of Absorbance Initial Concentrations decrease [NO 2 ] [CO] (/s) 1 x x x x x x x x a. write a consistent rate law expression for this reaction b. determine the value of the rate constant, k, including its units. c. what will the initial rate of the reaction be if each initial concentration is 2.0 x 10-3 M? d. a possible mechanism is given below; label the SLOW step and indicate any unstable intermediates NO 2 + NO 2 NO 3 + NO NO 3 + CO NO 2 + CO Write the equilibrium constant expression for the following reaction: 2 HI(g) H 2 (g) + I 2 (g) a. If K c = at 520 o C, calculate the concentrations of all species at equilibrium when 0.50 mol of HI is placed in a 5.0 L container. b. H for this reaction is -52 kj. How will the value of K c change if the temperature is increased to 700 o C? Why? Some typical problems to choose from 35. A solution contains the following salts in equal, dilute concentrations: NiF 2, ZnF 2, and CuF 2. Using inert electrodes, current is passed through the solution beginning with a very small voltage and gradually increasing the voltage to 4.5 volts. Give the order in which substances will be produced (and at which electrode) as the voltage is gradually increased. 36. What is the molar mass of glucose if 22.5 g gives a freezing point of o C when dissolved in 250 g (to the nearest 1 g) of water? (K f for water is 1.86 o C/m) 37. The solubility product constant, K sp, for silver bromide, AgBr, is 4.8 x When equal volumes of 2.0 x 10-3 M AgNO 3 and 2.0 x 10-3 M NaBr are mixed will a precipitate form? 38. Formic acid, HCHO 2, has a K a of 1.78 x For a 0.45 M solution of formic acid calculate [H + ], the ph, and the % dissociation. 39. A solution containing a +3 metal ion is electrolyzed by a current of 5.00 A for 10.0 min. What is the identity of the metal if 1.18 g of metal was plated out in this electrolysis. 40. A 10.0 ml sample of vinegar, an aqueous solution of acetic acid (CH 3 COOH), is titrated with M NaOH, and ml is required to reach the end point. a. What is the Molarity of the acetic acid? b. If the density of the vinegar is g/ml, what is the mass % of acetic acid in vinegar? FINAL EXAM MATERIALS 9

10 Some typical essay TOPICS to choose from 41. periodic properties and chemical/physical behavior 42. contrasting various types of bonds 43. buffer solutions 44. effects on reaction rate and collision theory 45. vapor pressure, structure and weak forces 46. fission and fusion [remember, prime candidates for essay topics include those things which we have spent time describing in some detail and which do not lend themselves to problem-solving; diagrams may be very useful in some cases] FINAL EXAM MATERIALS 10

11 Answers to Sample Final Exam 1. b 2. c 3. d 4. c 5. a 6. d 7. b 8. d 9. d 10. c 11. d 12. b 13. d 14. b 15. b 16. a 17. d 18. a 19. c 20. a 21. c 22. c 23. e 24. d 25. b 26. d 27. c 28. d 29. e 30. a 31. a mol gas b. Zn + 2 HCl ZnCl2 + H kj c g Zn d. zinc choride e kj 32. a kj/mol b J/mol K c kj/mol FINAL EXAM MATERIALS 11

12 33. a. rate = k[no2] 2 b. k = 2.0 x 10 4 /M 2 s c. rate = 8.0 x 10-2 /s d. NO3; first step is SLOW [H 2][I 2] 34. K c = 2 [HI] a. [H2] = [I2] = M, [HI] = M b. Kc at 700 < Kc at at the cathode: first Cu, then Ni, then Zn, then H2 at the anode: O2 only g/mol this is based on the net voltage in each case; the lowest net voltage occurs first until all of that substance is used up (or roughly, anyway ) 37. since Qsp = 1 x 10-6 >>> Ksp, then YES 38. [H + ] = 8.9 x 10-3 M, ph = 2.05, % ionization = 2.0% 39. Indium 40. a M b. 5.01% FINAL EXAM MATERIALS 12

Chemistry Exam Review

Chemistry Exam Review This exam review was compiled using the NC Essential Standards. You need to answer each question. You will receive multiple grades for your work. If you study everything on the exam