General Chemistry 1 Practice Exam 1 (Fall 2024) PDF

General Chemistry 1 Practice Exam 1 Content Instructions: Time yourself for 80 minutes. Use only the calculator, periodic table, and formula sheet that you would have access to on the actual exam. 1. Acetone, the main ingredient in nail polish remover, has a density of 791. kg/m3 at 25 C....

General Chemistry 1 Practice Exam 1 Content Instructions: Time yourself for 80 minutes. Use only the calculator, periodic table, and formula sheet that you would have access to on the actual exam. 1. Acetone, the main ingredient in nail polish remover, has a density of 791. kg/m3 at 25 C. What is this value in g/cm3? a. 7.91 x 10-4 g/cm3 b. 7.91 x 10-1 g/cm3 c. 7.91 x 103 g/cm3 d. 7.91 x 107 g/cm3 2. How many tungsten, W, atoms are in a spherical piece of jewelry with a diameter of 12.3 mm? The density of tungsten is 19.25 g/cm3. Vsphere = (4/3)r3 a. 6.14 x 1022 atoms b. 4.92 x 1023 atoms c. 2.08 x 1027 atoms d. 1.66 x 1028 atoms 3. Choose the species that does NOT have the same number of neutrons as 31P3- 31 a. P 35 b. K+ 29 c. Si 34 d. Ar 4. Consider the following difference in volume: 114. mL – 7. × 101 mL. Which of the following best represents the answer reported to the correct number of significant figures? a. 4. × 101 mL b. 44. mL c. 44.0 mL 5. The Green Fluorescent Protein (GFP), and its derivatives, are commonly used as biological markers in modern molecular biology experiments. The protein can absorb light at 395 nm, which transitions the protein from its ground electronic state (GS) to an excited electronic state (ES-A). The protein then transitions to another state (ES-B) before, finally, emitting light with a wavelength of 510 nm, which we see as green. Based on the information above, what can be concluded about the ordering of energy of GS, ES-A and ES-B from lowest energy to highest energy? a. GS < ES-A < ES-B b. GS = ES-B < ES-A c. GS < ES-B < ES-A d. GS = ES-A = ES-B 6. The following table contains data about nickel and silver: Element Molar mass (g/mol) Density (g/cm3) Nickel 58.69 8.90 Silver 169.87 10.49 Consider a pure nickel sphere and a pure silver sphere with identical volumes. Select a true statement about the spheres. a. They contain the same number of atoms b. They have the same mass c. They have the same radius d. They have the same total number of protons 7. Isotopic labeling (replacement of one or more atoms in a molecule with a different isotope of that atom) is a common technique used to investigate the structure, properties, and reactivity of a wide variety of chemical systems. Suppose 13C is used as an isotopic label and is substituted in place of 12C in a couple of locations on a complicated molecule made up of many carbons that is undergoing a reaction. What changed in the molecule? a. The total number of neutrons in the molecule b. The total number of protons in the molecule c. The total number of electrons in the molecule d. The total number of atoms in the molecule e. The total number of molecules in the sample 8. A specific molecular switch requires photons with a minimum frequency of 6.0 x 1014 Hz. Suppose that a lamp containing gaseous hydrogen atoms provides the photons for this task. Select the hydrogen atom electronic transition(s) that emit photons with a high enough frequency to activate the molecular switch. You may select one OR more answer(s). a. n = 7 to n = 5 b. n = 6 to n = 3 c. n = 4 to n = 2 d. n = 2 to n = 1 9. The mass of an electron is 9.11 x 10-31 kg. What is the mass of a mole of electrons (in g/mol)? a. 1.51 × 10-54 g/mol b. 1.51 × 10-51 g/mol c. 5.49 × 10-7 g/mol d. 5.49 × 10-4 g/mol 10. Which of the following quantities is NOT dependent on the  of a photon of light? a. The period b. The frequency c. The energy d. The wavelength e. The intensity 11. An atom of an isotope of an element has a mass of 5.148 x 10-23 g. Which element could the atom be? a. P b. V c. Cr d. He 12. Select the sample that consists of the greatest number of atoms a. 1.5 g Ne b. 1.5 g Ar c. 1.5 g graphite d. 1.5 g Al 13. Magnesium consists of three naturally occurring isotopes with the following percent natural abundances: Isotope % natural abundance 24 Mg 79 25 Mg 10 26 Mg 11 Which of the following best represents how to estimate the average atomic mass of Mg that appears on the periodic table? a. 79  24 amu + 10  25 amu + 11  26 amu b. (79  24 amu + 10  25 amu + 11  26 amu)  100 c. (79  24 amu + 10  25 amu + 11  26 amu) / 100 d. (79  24 amu + 10  25 amu + 11  26 amu) / 300 e. (24 amu + 25 amu + 26 amu) / 3 14. A wet sample of a solid compound was placed in an oven and dried. The initial mass of the sample was measured on Balance A and was reported as 15.813 g. The final mass of the sample, after it was heated, was measured on Balance B and was reported as 11.2 g. How should the mass of water lost from the sample, due to drying, be reported with correct number of significant figures? a. 27.013 g b. 27.0 g c. 4.613 g d. 4.61 g e. 4.6 g 15. Compare the electron in a hydrogen atom when it is in the n = 1 state to when the electron is in the n = 2 state. What is true about the relative energies of these states? a. The electron in the n = 1 state is more stable because it has a lower energy than when it is in the n = 2 state. b. The electron in the n = 1 state is more stable because it has a greater energy than when it is in the n = 2 state c. The electron in the n = 2 state is more stable because it has a lower energy than when it is in the n = 1 state. d. The electron in the n = 2 state is more stable because it has a greater energy than when it is in the n = 1 state 16. The number “10.81” is listed on the periodic table underneath the atomic symbol for Boron. Which of the following best describes the meaning of this value? a. An average Boron atom weighs 10.81 g; a mole of average Boron atoms weighs 10.81 amu. b. An average Boron atom weighs 10.81 amu; a mole of average Boron atoms weighs 10.81 g. c. Both an average Boron atom and a mole of average Boron atoms weigh 10.81 g. d. Both an average Boron atom and a mole of average Boron atoms weigh 10.81 amu. 17. The first ionization energy of Scandium (the amount of energy required to remove the outermost electron) is 1.05  10-18 J/atom. What is this value when you convert the units from J/atom to kJ/atom? a. 1.74  10-45 kJ/mol b. 1.74  10-42 kJ/mol c. 6.32 x 102 kJ/mol d. 6.32 x 105 kJ/mol 18. When a beam of electrons approaches two slits, diffraction patterns emerge that show regions of constructive and destructive interference. This result is evidence to support _____. a. The wave-like behavior of matter b. The wave-like behavior of light c. The particle-like behavior of matter d. The particle-like behavior of light 19. Zinc is an important “micronutrient” that is often added to commercially produced foods, such as cereals. One serving of a cereal contains 20% of the daily value of zinc, which is 2.2 mg. What is the recommended daily value of zinc, in mg? a. 0.44 mg b. 11. mg c. 44. mg d. 2.2 × 102 mg Open Ended: For these questions show your work including set up of dimensional analysis and any computation for which you may receive partial credit. Clearly indicate what the final numerical/textual answer is when appropriate by placing it in the correct line/box. OE1: The density of DNA is approximately 1.7 g/cm3. The mass of DNA inside a typical cell nucleus is about 6.5 pg. a. If the volume of a typical cell is about 1.0 x 103 m3, and the cell nucleus (where the DNA resides) is approximately 10% of this value, what is the typical volume of the cell nucleus? Report your answer to the correct number of significant figures in units of m3 b. What percentage of the volume of the cell nucleus is occupied by DNA? Report your answer to the correct number of significant figures. OE2: An electronic transition in the hydrogen atom coincides with the emission of a photon with a wavelength of 1.282 μm and originates from the n = 5 state. a. What is the final quantum state associated with this transition? b. Propose an electronic transition in the hydrogen atom that emits a photon of a higher frequency but originates from the same initial quantum number (ni) as the transition described in “part a.” OE 3: Consider the following table of densities of three elements: Element Density (g/cm3) Be 1.84 Si 2.33 Ti 4.5 a. The number density can be defined as the number of particles per unit volume. Calculate the number density of Si in units of atoms/cm3. b. The number density of Be is 1.23 × 1023 atoms / cm3 while the number density of Ti is 5.7 x 1022 atoms / cm3. Explain why this is true even though the density of Ti is larger than the density of Be.