Fall 2024 C103 Exam 2 Practice PDF

C103 Exam 2 Instructions & Provided information. Important instructions for completing C103 exams: 1. Use pencil or blue or black pen. 2. On scantron form, clearly write your first and last name as it is in canvas and your IU username. 3. On the short-answer sheet, clearly write your fir...

C103 Exam 2 Instructions & Provided information. Important instructions for completing C103 exams: 1. Use pencil or blue or black pen. 2. On scantron form, clearly write your first and last name as it is in canvas and your IU username. 3. On the short-answer sheet, clearly write your first and last name as it is in canvas and your IU username. Put your initials on all odd pages. 4. On the multiple choice exam sheet, put your first and last name on the first page. Exam Guidelines: You may use a scientific calculator (graphing is okay, but not required). No phones or smart watches or other electronic devices are allowed out during the exam. Being caught with an electronic device besides a calculator is considered academic misconduct. Sit in every other seat and row if possible (or assigned seat). Keep your eyes on your own papers. Students caught looking around may be asked to move to a seat at the front of the classroom. Useful Equations + Conversion Factors 𝑘𝑘𝑘𝑘 ∙ 𝑚𝑚2 1 𝐽𝐽 = 1 1 mi = 5280 ft (exact) 𝑠𝑠 2 1 km = 0.62137 mi 1 hr = 60 min = 3600 s (exact) 1 in = 2.54 cm (exact) °C = 5/9(°F - 32) 1 ft = 12 in (exact) °F = 9/5(°C) + 32 1 lb = 453.6 g K = °C + 273.15 1 gal = 3.7854 L Density = mass/volume 1 cal = 4.184 J (exact) 1𝐶𝐶𝐶𝐶𝐶𝐶 = 1 𝑘𝑘𝑘𝑘𝑘𝑘𝑘𝑘 = 1000 𝑐𝑐𝑐𝑐𝑐𝑐 = 4184 𝐽𝐽 = 4.184 𝑘𝑘𝑘𝑘 1 1 mL = 1 cm3 (exact) Kinetic energy: 𝐸𝐸𝑘𝑘 = 𝑚𝑚𝑣𝑣 2 2 ℎ 𝑞𝑞 deBroglie wavelength: 𝜆𝜆 = 𝑞𝑞 = 𝑚𝑚 ∙ 𝑐𝑐 ∙ ∆𝑇𝑇 𝑐𝑐 = 𝑚𝑚𝑚𝑚 𝑚𝑚∙∆𝑇𝑇 ℎ𝑐𝑐 −34 𝐸𝐸 = = ℎ𝑣𝑣 𝑐𝑐 = 𝑣𝑣𝑣𝑣 Planck’s constant: ℎ = 6.626𝑥𝑥10 𝐽𝐽 ∙ 𝑠𝑠 𝜆𝜆 Speed of light: 𝑐𝑐 = 3.00𝑥𝑥108 𝑚𝑚/𝑠𝑠 1 Avogadro's number (NA) = 6.022x1023 1𝐻𝐻𝐻𝐻 = = 𝑠𝑠 −1 1 mol “things” = 6.022x1023 “things” 𝑠𝑠 𝑚𝑚𝑚𝑚𝑚𝑚𝑚𝑚 𝑜𝑜𝑜𝑜 𝑒𝑒𝑙𝑙𝑙𝑙𝑙𝑙𝑙𝑙𝑙𝑙𝑙𝑙 𝑋𝑋 𝑖𝑖𝑖𝑖 1 𝑚𝑚𝑚𝑚𝑚𝑚 𝑜𝑜𝑜𝑜 𝑐𝑐𝑐𝑐𝑐𝑐𝑐𝑐𝑐𝑐𝑐𝑐𝑐𝑐𝑐𝑐 𝑚𝑚𝑚𝑚𝑚𝑚𝑚𝑚% 𝑒𝑒𝑒𝑒𝑒𝑒𝑒𝑒𝑒𝑒𝑒𝑒𝑒𝑒 𝑋𝑋 = × 100 𝑚𝑚𝑚𝑚𝑚𝑚𝑚𝑚 𝑜𝑜𝑜𝑜 1 𝑚𝑚𝑚𝑚𝑚𝑚 𝑜𝑜𝑜𝑜 𝑡𝑡ℎ𝑒𝑒 𝑐𝑐𝑜𝑜𝑜𝑜𝑜𝑜𝑜𝑜𝑜𝑜𝑜𝑜𝑜𝑜 Metric Conversion: Students should memorize metric conversions for kilo, centi, milli, micro and nano. Any other metric conversion needed will be provided in the question.  Fall 2024 C103 Exam 2 Practice Name: C103 Exam 2 Practice: Multiple Choice Section. There are 20 questions, each worth 2.5 points for a total of 50 points. 1. The existence of electrons in atoms of all elements was demonstrated by a. Millikan’s oil drop experiment b. Rutherford’s gold foil experiment c. Thomson’s cathode rate tube experiment d. Bohr’s atomic model 2. The mass of a proton is 1.6726x10-24 g and the mass of an electron is 9.1094x10-28 g. Around how many electrons would you need to equal the mass of one proton? a. 4 b. 6.0x102 c. 7.4 d. 1.8x103 e. 5.4x10-4 3. How many protons (p), neutrons (n), and electrons (e) are in a neutral atom of iodine-125? a. 53 p, 72 n, 53 e b. 53 p, 72 n, 72 e c. 72 p, 53 n, 53 e d. 72 p, 53 n, 72 e 4. How many of the following atoms have 2 unpaired electrons? I. C II. S III. Ti IV. Ca a. 0 b. 1 c. 2 d. 3 e. 4 5. How many of the following statements are true? I. An excited atom can return to its ground state by emitting electromagnetic radiation. II. The energy of electromagnetic radiation increases as its frequency decreases. III. The longer the wavelength of light, the greater its energy. IV. The frequency and wavelength of light are inversely proportional to each other. V. The energy of an atom is decreased when electromagnetic radiation is emitted from it. a. I, II, V b. II, III, V c. I, II, V d. I, II, IV e. I, IV, V 1 Fall 2024 C103 Exam 2 6. In an experiment searching for the photoelectric effect, and incident beam of blue light caused emission of electrons while a green light did not result in any emission of electrons. Which of the following sentences is (are) correct? I. A brighter green light may be able to cause emission of electrons. II. A red light will not be able to cause emission of electrons. III. A brighter blue light will cause emissions of more electrons. a. Only I is correct. b. Only II is correct. c. Only III is correct. d. Two of the statements are correct. e. All three statements are correct. 7. The nitrogen laser emits light at 3.371x102 nm. What is the energy of this light? a. 6.696x10-32 J b. 2.118x10-31 J c. 5.897x10-19 J d. 2.118x10-20 J 8. Based on the location of the elements on the periodic table, which of the following choices correctly labels the four compounds as ionic or molecular? a. Na2S = ionic; CO = ionic; CH4 = molecular; AlCl3 = ionic b. Na2S = ionic; CO = ionic; CH4 = ionic; AlCl3 = molecular c. Na2S = ionic; CO = molecular; CH4 = molecular; AlCl3 = molecular d. Na2S = molecular; CO = ionic; CH4 = ionic; AlCl3 = molecular e. Na2S = ionic; CO = molecular; CH4 = molecular; AlCl3 = ionic 9. Gallium has an atomic weight of 69.723 u and two stable isotopes. The Ga -69 (68.926 u) is 60.110% abundant. What is the mass (in unified atomic mass units, u) of the other isotope? a. 70.920 u b. 70.924 u c. 70.932 u d. 70.928 u e. 69.720 u 10. If 5.30x1023 atoms of element Y have a mass of 3.525 g, what is the identity of Y? a. Li b. He c. Kr d. Mg e. Mo 11. Which of the following has the largest number of moles of cations? a. 1 mol Na2S b. 2 mol AlCl3 c. 4 mol KBr d. 2 mol Li3N 2 Fall 2024 C103 Exam 2 12. An average cup of coffee contains 125 mg of caffeine, C8H10N4O2. How many nitrogen atoms are in 125 mg of caffeine? a. 6.44x10-4 N atoms b. 2.57x1023N atoms c. 3.88x1020 N atoms d. 1.55x1021 N atoms 13. What element is defined by the following information? p+ = 20 n° = 20 e- = 20 a. zirconium b. calcium c. potassium d. neon e. argon 14. Arrange the following spectral regions in order of increasing wavelength: infrared, microwave, ultraviolet, visible a. microwave < infrared < visible < ultraviolet b. microwave < visible < infrared < ultraviolet c. ultraviolet < infrared < visible < microwave d. ultraviolet < visible < infrared < microwave 15. Light can be made to have a higher intensity by raising its a. amplitude. b. energy. c. frequency. d. wavelength. 16. According to the Bohr model, when a hydrogen electron makes a transition from n=4 to n=2, which of the following statements is true? I. Energy is emitted. II. Energy is absorbed. III. Electrons lose energy. IV. Electrons gain energy. a. I only b. I and III c. I and IV d. II and IV 3 Fall 2024 C103 Exam 2 17. Which of the following elements will have unpaired electrons in the ground state? Ca, Li, C, F a. Ca, Li, C, and F b. Li, C, and F c. Li and F d. C and F 18. Atoms of which element, indicated by letter on the periodic table, have the orbital-filling diagram shown below? a. A b. B c. C d. D 19. Which of the following statements is true regarding the shape, size, and number of degenerate orbitals in s, p, and d orbitals? a. s orbitals are spherical, increase in size with increasing energy levels, and have 3 degenerate orbitals. b. p orbitals are dumbbell-shaped, increase in size with increasing energy levels, and have 3 degenerate orbitals. c. d orbitals are spherical, increase in size with increasing energy levels, and have 5 degenerate orbitals. d. p orbitals are clover-shaped, remain the same size regardless of energy level, and have 5 degenerate orbitals. 20. Calculate the empirical formula for a compound if a laboratory analysis of the compound determines the following mass percent composition: C = 60.00% H = 4.48% O = 35.53% a. CHO b. C2H2O c. C6H5O4 d. C9H8O4 4 Fall 2024 C103 E2 Practice Exam Short Answer Name: IU username Short Answer Section: Show all work to receive credit. Be sure to circle final answer. Worth 50 points. 1. Fill in the blanks to complete the table. (4 pts) Symbol Isotope Notation e.g., 190 (include charge if ion) 78𝑃𝑃𝑃𝑃 Mass number (A) 127 Atomic number (Z) Number of protons 53 Number of neutrons Number of electrons Charge -1 2. Find abundance of isotopes (4 pts). Must show all work for credit. Put final answer % abundances in the space below with 4 sig figs. Copper metal has two naturally occurring isotopes: copper-63 (isotopic mass = 62.93 u) and copper-65 (isotopic mass = 64.93 u). The weighted average atomic mass for copper as found on the periodic table is 63.55 u. Determine the abundance of both copper isotopes. Abundance Cu-63: % Abundance Cu-65: % 1  3. (10 pts) Complete the following calculations and conversions. Show all work and units. Provide all answers to 3 sig figs. Record final answer in indicated space. a. Determine the molar mass of an element if 1.46x1024 atoms of the element has a mass of 75.0 g. b. How many grams of NO2 are in 0.314 mol NO2 (nitrogen dioxide)? c. How many tin atoms are contained in 25.0 g of tin (Sn)? d. How many grams of hydrogen are in 35.0 g of C2H6 (ethane)? e. Determine the number of atoms of carbon in 22.3 moles of Al2(CO3)3 (aluminum carbonate) 2 Fall 2024 C103 E2 Exam INITIALS 4. Mass percent (4 pts). A compound has a formula of CoX2, where X is an unknown element. If this compound consists of 45.39% Co (cobalt) by mass: a. What is the molar mass of the compound? (4 sig figs) b. Using the compound’s formula and the molar mass of the compound, determine the element X. 5. Photoelectric effect (5 pts). The work function of gold metal is 491 kJ/mol. Calculate the maximum wavelength of light in nanometers that will cause the photoelectric effect for gold. Show all work and answer to 3 sig figs. 3  6. Periodic table (6 pts) a. Circle the alkali metals and put a letter a. in the circle. b. Circle the halogens and put a letter b. in the circle. c. Label the transition metals. d. Put a large “X” on the element that is in the 5 row and is a noble gas. e. Circle one element that would have similar reactivities and properties to calcium, Ca. Put the letter e. in the circle. f. What are the 7 elements that exist as diatomic gases at standard temperature and pressure? (either list them or circle them) 7. Atomic radius (4 pts) a. On the periodic table, which element has the smallest atomic radius? _______ b. On the periodic table, which element has the largest atomic radius? _______ c. What is the periodic trends for atomic radius and provide an explanation for the trends? 4 Fall 2024 C103 E2 Exam INITIALS 8. Wave/energy calculations (5 pts). Microwave ovens works by irradiating food with microwave radiation, which is absorbed and converted to heat. Show work and answer each to 3 sig figs. a. Assume that radiation from a microwave oven has a frequency of 2.50x109 Hz and all the energy is converted into heat. Calculate the energy of this radiation in J/photon. b. How much energy in joules, is needed to raise 400. g of water from 25.0°C to 95.0°C? (cw = 4.184 J/g°C) c. Determine the number of photons required to heat the water in part b. in a microwave with a frequency of 2.50x109 Hz. Number of photons (3 sig figs) ___________________photons 5  9. Electron configurations. (8 pts) a. Write the ground-state electron configuration for Al, aluminum (Z = 13). Al: _____________________________ b. Complete the electron orbital-filling diagram for Al, Aluminum. c. Using the electron configuration for Al, predict what charge that Al forms when it forms an ion by answering the following questions: Aluminum has _______valence electrons. In order to have a full outer s and p orbitals, Al could either gain _______electrons or lose ______electrons. It will be easier to gain/lose (circle one) electrons. This will result in Al ion being isoelectronic with _______ and have an overall _________charge (indicate + or – and the actual charge). d. Write the short-hand (noble gas core) ground-state electron configuration for Cd, cadmium (Z = 48). Cd: [ ]________________ e. Complete the electron orbital-filling diagram for Cd, cadmium (valence electrons only) 5s 4d f. Write the short-hand (noble gas core) ground-state electron configuration for Ag, silver (Z = 47). Ag: [ ]________________ g. Complete the electron orbital-filling diagram for Ag, silver (valence electrons only) 5s 4d 6