AP Chemistry Semester 1 Final Exam Practice Test (2022) PDF

.Name: _________________________ Period _______ AP CHEMISTRY SEMESTER 1 FINAL EXAM PRACTICE TEST Multiple Choice Compound Molar Mass (g/mol)...

.Name: _________________________ Period _______ AP CHEMISTRY SEMESTER 1 FINAL EXAM PRACTICE TEST Multiple Choice Compound Molar Mass (g/mol) CaO 56.1 SO2 64.1 V2O3 149.9 BaSO4 233.4 1. According to the information in the table above, a 1.00 g sample of which of the following contains the greatest mass of oxygen? a. CaO c. V2O3 b. SO2 d. BaSO4 2. M+ is an unknown metal cation with a +1 charge. A student dissolves the iodide of the unknown metal (chemical formula = MI) in enough water to make 100.0 mL of solution. The student then mixes the solution with excess AgNO3 solution, causing silver iodide (AgI) to precipitate. The student collects the precipitate by filtration, dries it, and records the data shown below. (The molar mass of silver iodide is 235 g/mol). Mass of metal iodide compound, MI 1.66 g Mass of filter paper 0.901 g Mass of filter paper + AgI precipitate 3.251 g What is the identity of the metal iodide compound, MI? a. lithium iodide, LiI c. potassium iodide, KI b. sodium iodide, NaI d. rubidium iodide, RbI 3. Complete combustion of a sample of a hydrocarbon in excess oxygen produces equimolar quantities of carbon dioxide and water. Which of the following could be the molecular formula of the compound? a. C2H2 c. C4H8 b. C2H6 d. C10H8 First Second Third Fourth Fifth Ionization Energy 801 2,430 3,660 25,000 32,820 (kJ/mol) 4. The first five ionization energies of a second-period element are listed in the table above. Which of the following correctly identifies the element and best explains the data in the table? a. The element is B because it has three valence electrons b. The element is B because it has five core electrons c. The Element is N because it has three electrons in the p sublevel. d. The element is N because it has five valence electrons 5. The photoelectron spectra of the 1s electrons of two isoelectronic species, Ca2+ and Ar, are shown above. Which of the following correctly identifies the species associated with peak X and provides a valid justification? a. Ar, because it has completely filled energy levels b. Ar, because its radius is smaller than the radius of Ca2+ c. Ca2+, because its average atomic mass is greater than the average atomic mass of Ar d. Ca2+, because its nucleus contains two more protons than the nucleus of Ar has. Element Atomic Radius First Ionization Energy Calcium 174 pm 590 kJ/mol Potassium ? ? 6. Based on periodic trends and the data in the table above, which of the following are the most probable values of the atomic radius and the first ionization energy for potassium? Atomic Radius First Ionization Energy (A) 144 pm 419 kJ/mol (B) 144 pm 633 kJ/mol (C) 196 pm 419 kJ/mol (D) 196 pm 633 kJ/mol 7. The mass spectrum of element X is presented in the diagram below. Based on this spectrum AND information from the periodic table, which of the following statements about element X is most likely to be true? a. Each isotope of element X contains 29 protons. 65 b. X has a greater effective nuclear charge than 63X 63 c. X has a higher ionization energy than 65X d. The average atomic mass of element X is between 64 and 65  8. A student prepared five solutions of CuSO4 with different concentrations, and then filled five cuvettes, each one containing one of the solutions. The cuvettes were placed in a spectrophotometer set to the appropriate wavelength for maximum absorbance. The absorbance of each solution was measured and recorded. The student plotted absorbance versus concentration, as shown in the figure above. Which of the following is the most likely explanation for the variance of the data point for the 0.40 M CuSO4 solution? a. The cuvette used for the 0.40 M solution had scratches on it, causing the light to be scattered. b. The cuvette used for the 0.40 M solution had not been wiped clean of fingerprints before it was placed in the spectrophotometer. c. The cuvette into which the 0.40 M solution was placed was filled slightly more than the other cuvettes. d. The cuvette into which the 0.40 M solution was placed had some water droplets inside. 9. The lattice energy of a salt (ionic compound) is related to the energy required to separate the ions. For which of the following pairs of ions is the energy that is required to separate the ions the largest? a. Mg2+ and O2- c. Na+ and F- b. Ba2+ and S2- d. K+ and Br- Questions 10-11 refer to the following information. 10. Consider the Lewis electron-dot diagrams for CO2 and SO2 and the electronegativity information in the table above. The molecular geometry and the polarity of the two substances CO2 and SO2 are a. the same, because the molecular formulas are similar. b. the same, because C and S have the same electronegativity values. c. different, because the lone pair of electrons on the S atom make it the negative end of a dipole. d. different, because S has a greater number of electron domains surrounding it than C has. 11. On the basis of the information in the table (on the previous page), which of the following has arranged these three bonds in order of INCREASING bond polarity? a. C-H < Si-Cl < S-F b. Si-Cl < C-H < S-F c. S-F < Si-Cl < C-H d. Si-Cl < S-F < C-H 12. Which of the following diagrams is most likely to represent the relative enthalpies of the reactants and products and the correct sign of ΔH for the combustion of CH4(g)? 13. Which of the following are the most probable values for the carbon-carbon bond length and bond energy in the substances C2H2 and C2H6? 14. A hot iron ball is dropped into a 200. g sample of water initially at 25°C. If 8.4 kJ of heat is transferred from the ball to the water, what is the final temperature of the water? (The specific heat of water is 4.2 J/g°C) a. 26°C c. 35°C b. 30°C d. 45°C  MgO(s) + 2HCl(aq) → MgCl2(aq) + H2O(l) ΔH° = -150 kJ/molrxn 15. In a certain experiment, 4.0 g MgO(s) is combined with 100. mL of 4.0 M HCl(aq) and allowed to react as completely as possible until one of the reactants is completely consumed. Which of the following identifies the limiting reactant and the amount of heat released in this experiment? (The molar mass of MgO is 40.3 g/mol) 16. Based on the bond energies shown in the table above, which of the following is the most accurate description of the reaction represented below? H2(g) + Cl2(g) → 2HCl(g) a. It is an endothermic reaction, and ΔHrxn = +190 kJ/molrxn b. It is an endothermic reaction, and ΔHrxn = +240 kJ/molrxn c. It is an exothermic reaction, and ΔHrxn = -190 kJ/molrxn d. It is an exothermic reaction, and ΔHrxn = -240 kJ/molrxn 17. A calorimetry experiment was performed in which two different samples of food were burned. The amount of heat released from the combustion of each food sample was transferred to water in a calorimeter. Based on the data in the table above, which of the following represents the most likely conclusion about the energy content for 1.0 g of each type of food? a. The combustion of 1.0 g of cashew releases less energy than the combustion of 1.0 g of marshmallow. b. The combustion of 1.0 g of cashew releases the same amount of energy as the combustion of 1.0 g of marshmallow. c. The combustion of 1.0 g of cashew releases more energy than the combustion of 1.0 g of marshmallow. d. No comparison can be made because the two systems started with different masses of food, different masses of water, and different initial temperatures. 18. If it is possible to draw more than one Lewis electron-dot structure for a molecule or ion, there are certain guidelines for choosing the more dominant Lewis structure. Which of the following Lewis structures is the most dominant based on the guidelines shown above? 19. Which of the following has correctly identified both the hybridization of the nitrogen atom and the H-N-H bond angle present in the NH3 molecule? 20. In a certain experiment, 1.22 g of benzoic acid, C6H5COOH, is dissolved in water and titrated with a solution of NaOH. Benzoic acid is a monoprotic acid. The equivalence point in the titration is reached when 50.0 mL of the base solution is added. (The molar mass of C6H5COOH) is 122 g/mol.) What is the concentration of the NaOH solution used in this titration experiment? a. 2.00 x 10-4 M c. 0.200 M b. 0.100 M d. 0.500 M 21. In a certain experiment, 24.0 grams of H2 reacted with 48.0 grams of O2 until one of the reactants was completely consumed. What is the theoretical yield of H2O? a. 27.0 g c. 54.0 g b. 36.0 g d. 72.0 g 22. The table above contains information about samples of three different gases at 273 K. The samples are in three identical rigid containers numbered 1 through 3. The best explanation for the lower pressure in container 3 is that SO2 molecules a. have a larger average speed than the other two gases. b. have stronger intermolecular attractions than the other two gases. c. occupy a larger portion of the container volume than the other two gases.  d. contain 𝝅 bonds, while the other gases contain only 𝛔 bonds. 23. The reaction between NO(g) and O2(g) to produce NO2(g) in a rigid reaction vessel is represented in the diagram above. The pressure inside the container is recorded using a pressure gauge. Which of the following statements correctly predicts the change in pressure as the reaction goes to completion at constant temperature, and provides the correct explanation? a. The pressure will increase because the product molecules have a greater mass than either of the reactant molecules. b. The pressure will decrease because there are fewer molecules of product than of reactants. c. The pressure will decrease because the product molecules have a lower average speed than the reactant molecules. d. The pressure will not change because the total mass of the product molecules is the same as the total mass of the reactant molecules. Questions 24-25 refer to the following: CH3OH(g) → CO(g) + 2H2(g) ΔH° = +91 kJ/molrxn The reaction represented above goes essentially to completion. The reaction takes place in a rigid, insulated vessel that is initially at 600 K. 24. Which of the following describes what happens to the temperature of the contents of the vessel as the reaction occurs and provides the correct justification? a. The temperature must increase, because the molecules move faster as the reaction proceeds. b. The temperature must decrease, because the reaction takes place at a temperature that is higher than room temperature. c. The temperature must decrease, because the reaction is endothermic. d. The temperature does not change, because the vessel is insulated. 25. A sample of CH3OH(g) is placed in the previously evacuated vessel with a pressure of 3.0 atm at 600 K. What is the final pressure in the vessel after the reaction is complete and the contents of the vessel are returned to 600 K? a. 1.0 atm c. 6.0 atm b. 3.0 atm d. 9.0 atm 26. In a paper chromatography experiment, a sample of a pigment is separated into two components, X and Y, as shown in the figure above. The surface of the paper is moderately polar. What can be concluded about X and Y based on the experimental results? a. X has a larger molar mass than Y does. b. Y has a larger molar mass than X does. c. X is more polar than Y. d. Y is more polar than X. 27. The particle diagrams above represent aqueous solutions of acids HX and HY. Water molecules are omitted for clarity. Based on the information in the diagrams above, which of the following best represents the correct net-ionic equation for the reaction between NaOH(aq) and each acid? 28. A mixture containing equal numbers of moles of pentane and octane was separated using distillation. Based on the diagrams shown above, which of the following identifies the substance that would be initially present in higher concentration in the distillate and correctly explains why that occurs? a. pentane, because it has fewer C-C bonds to break b. pentane, because it has a shorter carbon chain and weaker London dispersion forces c. octane, because it has more C-C bonds to break d. octane, because it has a longer carbon chain and stronger London dispersion forces 29. Beaker X and beaker Y each contain 1.0 L of solution, as shown above. A student combines the solutions by pouring them into a larger, previously empty beaker Z and observes the formation of a yellow precipitate. Assuming that the volumes are additive, which of the following sets of solutions could be represented by the diagram above? 30. The structural formulas for ethane and butane are shown above. Which compound has the higher boiling point, and why is that compound’s boiling point higher? a. butane, because it has more hydrogen atoms, resulting in more opportunities to form hydrogen bonds with neighboring molecules. b. butane, because it has more electrons, resulting in greater polarizability and stronger dispersion forces. c. ethane, because its molecules are smaller and they can get closer to one another, resulting in stronger coulombic attractions between molecules. d. ethane, because its molecules have a greater dipole moment and experience stronger dipole-dipole attractions. 31. Under which of the following conditions of temperature and pressure will H2 gas be expected to behave most like an ideal gas? a. 50 K and 0.10 atm c. 500 K and 0.10 atm b. 50 K and 50. atm d. 500 K and 50. atm 32. Which of the following diagrams best illustrates the hydrogen bonding interaction between two molecules of methanol, CH3OH? 33. Which of the following best helps to explain why the value of ΔH° for the dissolving of CaF2 in water is positive? a. When CaF2(s) dissolves in water, the temperature of the solution increases. b. When CaF2(s) dissolves in water the solution is able to conduct electricity. c. Ca2+ ions have very strong ion-ion interactions with F- ions in the crystal lattice. d. Ca2+ ions have very strong ion-dipole interactions with water molecules in the solution.  34. Based on the information in the table above, which liquid, CS2(l) or CCl4(l), has the higher equilibrium vapor pressure at 25°C, and why? a. CS2(l), because it has stronger London dispersion forces. b. CS2(l), because it has weaker London dispersion forces. c. CCl4(l), because it has stronger London dispersion forces. d. CCl4(l), because it has weaker London dispersion forces. 35. A student mixes 50 mL of 0.10 M NaCl with 50 mL of 0.20 M AgNO3 to form AgCl(s). Which of the diagrams below best represents the ions that are present in significant concentrations in the solution after the reaction is complete? 36. In a certain experiment, 100. mL of 6.0 M HCl(aq) is added to 10.6 g of Na2CO3(s). Bubbles of CO2(g) are produced during the reaction, which proceeds until one of the reactants is completely consumed. What is the theoretical yield NaCl(s) that should be present in the solution at the end of the reaction? (The molar masses of Na2CO3 and NaCl are equal to 106.0 and 58.5, respectively.) a. 5.85 g NaCl c. 11.7 g NaCl b. 10.6 g NaCl d. 14.6 g NaCl Questions 37-38 refer to the following reaction Fe(s) + 2HCl(aq) → FeCl2(aq) + H2(g) 37. When a student adds 30.0 mL of 1.00 M HCl(aq) to 0.56 g of powdered Fe(s), a reaction occurs according to the equation above. When the reaction is complete at 273 K and 1.0 atm, which of the following is true? a. 0.010 mol of Fe remains unreacted b. 0.020 mol of HCl remains unreacted c. 0.015 mol of FeCl2 has been produced d. 0.22 L of H2 has been produced 38. Which element is being reduced in the reaction shown above, and what is the element’s change in oxidation number? a. iron, which changes from 0 to +2 b. hydrogen, which changes from +1 to 0 c. chlorine, which changes from 0 to -1 d. chlorine, which changes from -1 to -2 39. The distribution of speeds of H2(g) molecules at 273 K and 1 atm is shown in the diagram above. Which of the following best shows the speed distribution of He(g) atoms under the same conditions of temperature and pressure? 40. A sample of pure CO2(g) in a rigid container has a pressure of 2 atm at a temperature of 0°C. What is the approximate density of this gas sample? a. 1 g/L c. 3 g/L b. 2 g/L d. 4 g/L 41. Which of the following reactions is not thermodynamically favored at low temperatures but becomes favored as the temperature increases?  2K(s) + Cl2(g) → 2KCl(s) ΔH° = - 872 kJ/molrxn 42. It is observed that the reaction above goes essentially to completion. Which of the following is a true statement about the thermodynamic favorability of the reaction? a. The reaction is favorable and driven by an enthalpy change only. b. The reaction is favorable and driven by an entropy change only. c. The reaction is favorable and driven by both enthalpy and entropy changes. d. The reaction is unfavorable due to both enthalpy and entropy changes. 43. Which of the following processes involves the greatest increase in entropy? a. SO3(g) + H2(g) → SO2(g) + H2O(g) b. N2(g) + 3H2(g) → 2NH3(g) c. C2H2(g) + 2H2(g) → C2H6(g) d. MgSO3(s) → MgO(s) + SO2(g) 44. A certain reaction is thermodynamically favored at temperatures below 400. K, but it is not favored at temperatures above 400. K. The value of ΔH° for the reaction is -20 kJ/mol. What is the value of ΔS° for the reaction? (assume that ΔH° and ΔS° do not change with temperature.) a. -50 J/molK c. -0.050 J/molK b. -20 J/molK d. 50 J/molK 45. Two types of electromagnetic radiation, X and Y, are represented in the data table above. Which of the following are the most probable values for wavelength and energy associated with Y? (You should not do any calculations here...use your understanding of the relationships) a. 1 x 10-20 m, 2 x 10-5 J b. 1 x 10-20 m, 2 x 10-19 J c. 1 x 10-6 m, 2 x 10-5 J d. 1 x 10-6 m, 2 x 10-19 J 46. Which of the following statements is most closely associated with the photoelectric effect? a. Light shining on a clear metal surface causes the surface to emit electrons. b. Energy is emitted by electrons as they travel from a higher energy state toward a lower energy state. c. Electrons exist only in certain discrete energy levels, which are described by quantum numbers. d. The solution to Schrodinger’s equation for the hydrogen atom yields a set of wave functions called orbitals. Free-Response 1. A student is given a sample of a pure, anhydrous salt. The identity of this salt is one of the three substances listed in the table above. a. The student measures out 1.00 g of the unknown salt and dissolves it completely into 100. mL of distilled water. This solution contains carbonate ions. In the box below, complete a particle diagram that includes four water molecules with proper orientation around the carbonate ion. Represent water molecules as b. The student then adds 25 mL of 1.6 M CaCl2(aq) to the solution prepared in part (a). After mixing the resulting solution thoroughly, a solid precipitate is formed which contains carbonate ions. i. Calculate the number of moles of CaCl2 added to the solution of the unknown salt during this step in the experiment. ii. Write the balanced net-ionic equation for the formation of the precipitate. c. The precipitate formed in this experiment is filtered, dried, and weighed. Data from the experiment is shown in the table above. i. Calculate the mass of the precipitate recovered from this experiment: ___________________________________ ii. Calculate the number of moles of the precipitate recovered from this experiment. Show your work below, and round your answer to the proper number of significant figures. iii. The formula that is most likely to represent the identity of the unknown salt used in this experiment is [ Li2CO3 | Na2CO3 | K2CO3 ] iv. Show your work below for the calculation, based on laboratory data, that provides the best evidence for the formula you circle in part (c)(iii). d. When an aqueous solution of the unknown salt is mixed with 1.0 M HCl(aq), a reaction occurs in which bubbles of gas are observed. Write the balanced net-ionic equation for this reaction. 2. The structural formula of benzoic acid (C6H5COOH) is shown above. a. Identify the hybridization of the carbon atom indicated by the arrow in the diagram above. _____________ b. The table above shows information about benzoic acid and acetophenone. i. Identify all of the intermolecular forces each substance experiences. benzoic acid ________________________________________________________________________________ acetophenone ______________________________________________________________________________ ii. Make a prediction regarding the boiling point of acetophenone by selecting one of the statements below. __________ The boiling point of acetophenone is less than 522 K __________ The boiling point of acetophenone is equal to 522 K __________ The boiling point of acetophenone is greater than 522 K iii. Justify the prediction you made in part (ii) by comparing the strengths of the intermolecular forces you identified in part (i) c. It is known that the combustion of 1.00 g of benzoic acid produces 26.4 kJ of heat. i. Balance the following combustion equation using the lowest possible whole numbers as coefficients: _________C6H5COOH(s) + _____________ O2(g) → ________________ CO2(g) + __________________ H2O(l) ii. Calculate the change in enthalpy, ΔH, for the balanced equation written in part (b)(i). Show your work below, and express your answer in units of kJ/molrxn. Make sure to include the sign of ΔH, in your answer.  iii. In a certain experiment, 2.25 g of benzoic acid was burned completely in a bomb calorimeter. Calculate the amount of heat released from the combustion of 2.25 g of benzoic acid. iv. Assuming that all of the heat generated from the combustion of 2.25 g of benzoic acid is completely transferred to a 500. g sample of water (specific heat 4.18 J/g°C) at 25.0°C, calculate the final temperature you would expect to observe in this sample of water after it is heated. 3. Answer the following questions about the substances CO, Cl2, and COCl2. a. In the boxes below, complete the Lewis electron-dot diagrams for each molecule by drawing all of the bonding and nonbonding electron pairs. Each atom should obey the octet rule. In the diagram for the COCl2 molecule, the formal charge on each atom should be equal to zero. b. Although the atoms in the Lewis diagram for the CO molecule obey the octet rule, the formal charge on each atom is not zero. Based on the Lewis diagram for CO that you drew in part (a), calculate the formal charge of each atom. Formal Charge on C: _____________________________ Formal Charge on O: _________________________________ c. Fill in the missing information in the table below for the COCl2 molecule.  d. Use the data from the table above to calculate the value of ΔH for the following reaction. CO(g) + Cl2(g) → COCl2(g) 4. Samples of CO(g) and Cl2(g) are placed in separate 1.0 L containers at 25°C. The pressure in each flask is shown in the diagram above. Answer the following questions about these two gas samples. a. Indicate whether the average kinetic energy of the CO(g) molecules is less than, equal to, or greater than the average kinetic energy of the Cl2(g) molecules. Justify your answer with a claim, evidence, reasoning statement. b. Indicate whether the average speed of the CO(g) molecules is less than, equal to, or greater than the average speed of the Cl2(g) molecules. Justify your answer with a claim, evidence, reasoning statement. c. Calculate the mass of CO(g) present in the flask on the left. Show your work. CaO(s) + H2O(l) → Ca(OH)2(s) ΔH°rxn = -63.7 kJ/molrxn 5. Calcium oxide, CaO(s), has been proposed as a substance that can be used to heat water quickly for portable heating packs or for cooking. When placed in water, CaO(s) reacts as shown by the equation above. a. A student wants to design a heating pad that could heat a 150.0 g sample of water from 25.0°C to 60.0°C. Calculate the amount of heat, in joules, that the water must absorb for its temperature to change by this amount. Assuming the specific heat capacity of the water is 4.18 J/(g°C).  b. Calculate the minimum mass of CaO(s) that the student would need to use in order to cause the temperature change described in part (a). Show all work. c. The student hypothesizes that the design of the heating pad could be changed to enable it to heat 150.0 g of water from 25.0°C to 90.0°C by using a greater mass of CaO(s). i. Use the data in the table below to determine the standard entropy change, ΔS°rxn, in J/(Kᐧmolrxn) for the reaction. ii. Is the reaction thermodynamically favorable at 90.0°C? Justify your answer with a calculation. Assume that both ΔS°rxn and ΔH°rxn are constant between 25.0°C and 90.0°C. 6. A certain light source produces yellow light with a wavelength of 580 nm. a. Calculate the frequency of this light in units of s-1. Show your work. b. Calculate the energy of a single photon of this light in units of joules. Show your work. c. The Br-Br bond has a bond energy of 192 kJ/mol. Does light with a wavelength of 580 nm have sufficient energy to break the Br-Br bond? Justify your answer with a calculation. d. A different light source that emits infrared light is shined on a sample of Br2 molecules. i. The wavelength of infrared light is [ shorter | longer ] than 580 nm. ii. The frequency of infrared light is [ lower | higher ] than the frequency of yellow light. iii. Therefore, the energy associated with infrared light is [ lower | higher ] than the value that was calculated in part (b) for yellow light. iv. It is likely that infrared radiation [ would | would not ] have sufficient energy to break the Br-Br bond.