Chemistry Exam Review 1. Generally, observed behavior that can be formulated into a statement, sometimes mathematical in nature, is called a(n) a. Observation b. Measurement c. Theory d. Natural law e. experiment 2. Convert 0.2974 m to mm f. 297.4 mm g. 2.974 x 10^-3 mm h. 2.974 x 10^4 mm i. 0.02974 mm j. None of these 3. As part of the calibration of a new laboratory balance, a 1.000 g mass is weighted with the following results: TRIAL MASS 1 1.201 +- 0.001 2 1.202 +- 0.001 3 1.200 +- 0.001 The balance is : a) Both accurate and precise b) Accurate but imprecise c) Precise but inaccurate d) Both inaccurate and imprecise e) Accuracy and precision are impossible to determine with the available information 4. How many sig figs are there in the number 0.0006313? a. 7 b. 3 c. 8 d. 4 e. 0 5. The pressure of the earth’s atmosphere at sea level is 14.7 lb/in ^2. What is the pressure when expressed in g/m^2? (2.54cm - in, 2.205 lb - 1 kg) a. b. c. d. e. 2.62 x 10^5 g/m^2 1.03 x 10^7 g/m^2 5.02 x 10^4 g/m^2 4.30 x 10^0 g/m^2 2.09 x 10^-5 g/m^2 6. An example of a pure substance is a. Elements b. Compounds c. Pure water d. Carbon dioxide e. All of these 7. Which of the following pairs of compounds can be used to illustrate the law of multiple proportions? NH₄ and NH₄CL a. ZnO₂ and ZnCl₂ b. H₂O and HCL c. NO and NO₂ d. CH₄ and CO₂ 8. Which one of the following statements about atomic structures is false? a. An atom is mostly empty space b. Almost all of the mass of the atom is concentrated in the nucleus c. The protons and neutrons in the nucleus are very tightly packed d. The number of protons and neutrons is always the same in the neutral atom e. All of the above statements (A-D) are true. 9 - 18 missing 9. Bromine exists naturally as a mixture of bromine-79 and bromine-81 isotopes. An atom of bromine-79 contains Ans: 35 protons, 44 neutrons, and 35 electrons 10. Which of the following atomic symbols is incorrect (A) 14/6 C (B) 37/17 Cl (C) 32/15 P (D) 39/19 K (E) 14/8 N 11. A species with 12 protons and 10 electrons is Ans: Mg2+ 12. Which of the following names is incorrect? a. cobalt(II) chloride b. magnesium oxide c. aluminum (III) oxide d. diphosphorus pentoxide e. all are correct 13. The correct name for LiCl Ans: lithium chloride 14. All of the following are in aqueous solution. Which is incorrectly named? Ans: D (HCN Cyanic acid) 15. How many atoms (total) are there in one formula unit of Ca3(PO4)2? Ans: 13 16. A hypothetical element consists of two isotopes of masses 86.95 amu and 88.95 amu with abundances of 35.5% and 65%, respectively. What is the average atomic mass of this element Ans: 88.2 amu 17. What is the mass of 4 atom(s) of copper in grams? Ans: 4.22x10^-22g 18. A mixture of KCl and KNO3 is 44.20% potassium by mass. The percentage of KCl in the mixture is closest to Ans: 40% 19. What is the coefficient for water when the following equation is balanced? As(OH)3(s) + H₂SO₄(aq) → As₂(SO₄) + H₂O(l) a. 1 b. 2 c. 4 d. 6 e. 12 20. wPCL5 + xH2O → yPOCl3 + zHCL a. b. c. d. e. The above equation is properly balanced when: W = 1, x = 2, y = 2, z = 4 W = 2, x = 2, y = 2, z = 2 W = 2, x = 2, y = 2, z = 1 W = 1, x = 1, y = 1, z = 2 None of these 21. How many grams of Ca(NO₃)₂ can be produced by reacting excess HNO₃ with 6.55 g of Ca(OH)₂? a. 7.25g b. 14.5 g c. 29.0g d. 13.1 g e. 6.55 g 22. When rubidium metal is exposed to air, two atoms of rubidium, Rb, combine with one atom of oxygen. If 1.32 grams of rubidium is exposed to air, what will be the mass of the product in grams? a. 17.32g b. 1.44g c. 9.32g d. 5.77g e. 2.89g 23. All of the following reactions 2Al(s) + 3Br₂(l) → 2AlBr₃(s) 2Ag₂O(s) → 4Ag(s) + O₂(g) CH₄(l) + 2O₂(g) → CO₂(g) + 2H₂O(g) Can be classified as a. Oxidation-reduction reaction b. Combustion reaction c. Precipitation reaction d. A and B e. A and C 24. When solutions of strontium chloride and sodium carbonate react, which of the following is a spectator ion? a. Strontium chloride b. Chloride ion . c. Sodium-ion . d. Carbonate ion e. Two of these 25. If all of the chloride in a 4.776-g sample of an unknown metal chloride is precipitated as AgCl with a 70.90 mL of 0.2010 M AgNo₃, what is the percentage of chloride in the sample? a. 50.52% b. 10.58% c. 1.425% d. 9.454% e. None of the above 26. What mass of NaOH is required to react exactly with 25.0 mL of 3.0 M H₂SO₄ ? a. 3.0 g b. 0.7g c. 6.0g d. 150g e. None of these 27. Given the reaction: 2MnO₄⁻+ 5H₂O₂ + 6H⁻ → 2Mn²⁺ + 8H₂O +5O₂ , determine the number of electrons involved in this reaction. a. 10 b. 8 c. 6 d. 4 e. 2 28. A physics experiment is conducted at a pressure of … kPa. What is this pressure in mmHg? a. 18.4 mmHg b. .. c. 1.40 x … d. 105 mmHg e. 1.84 x 10 ^-2 mmHg 29. A gas sample is held at a constant pressure. The gas occupies 3.62 L of volume when the temperature is 21.6 ℃. Determine the temperature at which the volume of the gas is 3.45 . a. 309 K b. 281 K c. 20.6 K d. 295 K e. 554 K 30. What volume of H₂O(g) measured at STP is produced by the combustion of 3.85 g of natural gas (CH₄) according to the following equation? CH₄(g) + 2O₂(g) → CO₃(g) + 2H₂O(g) a. 5.38 L b. 10.8 L c. 2.69 L d. 11.7 L e. 1.93 L 31. Given the equation: 2KClO₃(s) → 2KCl(s) + 3O₂(g) A 3.00 g sample of KClO₃ is decomposed and the oxygen at 24.0 ℃ and 0.991 atm is collected. What volume of oxygen gas will be collected assuming 100% yield? a. 6.02 x 10^2 mL b. 7.30 x 10^1 mL c. 9.03 x 10^2 mL d. 4.01 x 10^2 mL e. None of these 32. Consider the reaction: C₂H₅OH(l) + 3O₂(g) → 2CO₂(g) + 3H₂O(l); ΔH = -1.37 x 10^3 kJ Consider the following propositions: I. The reaction is endothermic II. The reaction is exothermic III. The enthalpy term would be different if the water formed was gaseous. Which of these propositions is (are) true? a. b. c. d. e. I II III I, II II, III 33. A 18.3 g piece of aluminum (which has a molar heat capacity of 24.03 J/ ℃ * mol) is heated to 82.4 ℃ into a calorimeter containing water (specific heat capacity of water is 4.18 J/ ℃ * mol) initially at 22.3 ℃. The final temperature of the water is 25.8 ℃. Ignoring significant figures, calculate the mass of water in the calorimeter a. 63.1 g b. c. d. e. 1.70 kg 1.91 g 923 g None of these 34. What is the enthalpy change when 40.1 mL of 0.400 M sulfuric acid reacts with 19.5 mL of 0.133 M potassium hydroxide? H₂SO₄(aq) + 2KOH(aq) → K₂SO4(aq) + 2H₂O(l) , ΔH° = - 111.6 kJ/ mol a. b. c. d. e. -0.145 kJ -2.08 kJ -1.79 kJ -0.289 kJ -112 kJ 35. At 25 ℃, the following heats of reaction are known: ΔH (kJ/mol) 2ClF + O₂ → C₂lO + F₂O : 167.4 2ClF₃ + 2O₂ → Cl₂O + 3F₂O : 341.4 2F₂ + O₂ → 2F₂O : -43.4 At the same temperature, calculate ΔH for the reaction: ClF + F₂ → ClF₃ a. b. c. d. e. -217.5 kJ/mol -130.2 kJ/mol +217.5 kJ/mol -108.7 kJ/mol None of these 36. What is the wavelength of a photon of red light (in nm) whose frequency is 4.64 x 10^14 Hz? a. b. c. d. e. 646 nm 1.55 x 10^5 nm 155 nm 464 nm None of these 37. Which one of the following types of radiation has the shortest wavelength, the greatest energy, and the highest frequency? a. Ultraviolet radiation b. Infrared radiation c. Visible red light d. Visible blue light e. None, because short wavelength is associated with low energy and low frequency, not high energy and high frequency. 38. Which of the following statements is false? a. b. c. d. An orbital can accommodate at most two electrons. The electron density at a point is proportional to ψ² at that point. The spin quantum number of an electron must be either +½ or -½. A 2p orbital is more penetration than a 2s: i.e., it has a higher electron density near the nucleus and inside the charge cloud of a 1s orbital. e. In the unusual order of filling, the 6s orbital is filled before the 4f orbital. 39. Which of the following electron configurations is correct? a. b. c. d. e. Ga: [Kr]4s²3d¹⁰4p¹ Mo: [Kr] 5s²4d⁵ Ca: [Ar]4s¹3d¹⁰ Br: [Kr] 4s²3d¹⁰4p⁷ Bi: [Xe]6s²4f¹⁴5d¹⁰6p³ 40. Which of the following processes represents the ionization energy of bromine? a. b. c. d. e. Br(s) → Br⁺(g) + e⁻ Br(l) → Br⁺(g) + e⁻ Br(g) → Br⁺(g) + e⁻ Br(s) → Br⁺(s) + e⁻ Br₂(s) → Br₂⁺(g) + e⁻ 41. For the elements Cs, F and Cl, the order of increasing electronegativity is a. b. c. d. e. F < Cl < Cs Cs < Cl < F Cl < Cs < F F < Cs < Cl None of these 42. When molten sulfur reacts with chlorine gas a vile-smelling orange liquid forms that is found to have the empirical formula SCl. Which of the following could be the correct Lewis structure for this compound E. 43. Which of the following has an incomplete octet in its Lewis structure? a. SO₂ b. ICl c. CO₂ d. F₂ e. NO 44. How many resonance structures can be drawn for the molecule O₃? a. 1 b. 2 c. 3 d. 4 e. 5 45. Which of the following types of molecules always has a dipole moment? a. Linear molecules with two identical bonds b. Tetrahedral molecules (four identical bonds equally spaced). c. Trigonal pyramid molecules (three identical bonds). d. Trigonal planar molecules (three identical bonds equally spaced). e. None has a dipole moment. 46. NI₃ a. Pyramidal b. Tetrahedral c. Square planar d. Octahedral e. None of these 47. Using the following bond energies: Bond: , Bond Energy: C = C, 839 C - H, 413 O = O, 495 C = O, 799 O - H, 467 Estimate the heat of combustion for one mole of acetylene: C₂H₂(g) + ½ O₂(g) → 2CO₂(g) + H₂O(g) a. 1228 kJ b. -1228 kJ c. -447 kJ d. +447 kJ e. +365 kJ