Fall 2023 CHEM 1113 Exam 3 final version

pdf

School

University of Colorado, Boulder *

*We aren’t endorsed by this school

Course

1113

Subject

Chemistry

Date

Jan 9, 2024

Type

pdf

Pages

Uploaded by PrivateUniverse6512

CHEMISTRY 1113 EXAM 3 November 7, 2023 Drs. Carlon, Pochas, & Wise P LEASE READ THIS COVER PAGE AND FOLLOW THE INSTRUCTIONS . D O NOT OPEN THE EXAM UNTIL YOU ARE TOLD TO DO SO . On the computer graded answer sheet in the appropriate boxes, enter your: 1. name 2. student identification number 3. recitation section (In the four columns labeled “Section ID”, using a zero before your recitation section number. Ex., section 231 is written as 0231.) Then fill in the corresponding bubbles below your name, ID number, and recitation section. Answer all questions on the computer graded answer sheet by filling in the proper bubble with a No. 2 pencil. If you change an answer, erase the undesired mark thoroughly. Mark only the best answer to each question. Cell phones must be turned off; all electronic devices must be placed in a backpack or on the floor and may not be accessed during the exam. Students violating this policy will be asked to leave and will receive a zero for the exam. A Periodic Table is printed on the back of this cover sheet. There are 5 exam pages (double-sided) with 25 questions. Each question is worth 6 points for a total of 150 points. Scratch paper is attached to the back of the exam. When you are instructed to begin the exam, please check that you have all the pages. When you are finished, give the answer sheet to your teaching assistant. You may take the exam with you. Answers will be posted on the Canvas class webpage at the completion of the exam. Good luck! Useful Information: 1 atm = 760 torr = 760 mmHg R = 0.08206 ?∙𝑎?? ???∙? 1 J = 1 ?𝑔∙? 2 ? 2 𝑃 1 𝑉 1 ? 1 𝑇 1 = 𝑃 2 𝑉 2 ? 2 𝑇 2 PV = nRT ?𝑎?𝑒 ? ?𝑎?𝑒 ? = √ ?? ? ?? ? 𝑃 ???𝑎? = 𝑃 ? + 𝑃 ? + ⋯ 𝑃 𝑋 = 𝑋 𝑥 𝑃 ???𝑎? , 𝑤ℎ𝑒𝑟𝑒 𝑋 ? = ? ? ? 𝑡?𝑡𝑎𝑙 𝑐 = 𝜆𝜐 Δ𝐸 = ℎ𝜐 = ℎ𝑐 𝜆 Speed of light: c = 2.998 × 10 8 m/s Planck’s constant : h = 6.626  10 – 34 J∙s 1 𝜆 = 1.097 × 10 7 𝑚 −1 ( 1 ? 𝑙?𝑤 2 − 1 ? ℎ𝑖?ℎ 2 ) ∆𝐸 = −2.18 × 10 −18 𝐽 ( 1 ? ?𝑖?𝑎𝑙 2 − 1 ? 𝑖?𝑖𝑡𝑖𝑎𝑙 2 ) De Broglie 𝜆 = ℎ ?𝑣

Cn Nh Fl Mc Lv 117 Ts (293) Og

CHEMISTRY 1113 Exam 3 Page 1 of 5 1. Which of the following assumptions about an ideal gas is not correct? A. The gas particles have a negligible volume. B. The gas particles exert attractive forces on each other. C. The gas particles are in constant random motion. D. The gas particles have an average kinetic energy proportional to the absolute temperature. 2. Which represents the result of increasing the temperature and decreasing the pressure on a fixed amount of gas in a balloon? A. B. C. D. 3. What pressure change would occur if the temperature and volume are both doubled, but the number of moles remain fixed? A. The pressure would not change. B. The pressure would reduce to ¼ of the original C. The pressure would double. D. The pressure would increase by a factor of 4 4. 6.0 moles of an ideal gas occupy a container with a volume of 100.0 L at a temperature of 25 °C. What is the pressure inside the container? A. 750 torr B. 15,000 torr C. 0.12 atm D. 1.5 atm 5. A flask with a volume of 3.16 L contains 9.33 grams of an unknown gas at 32.0°C and 1.00 atm. What is the molar mass of the gas? A. 7.76 g/mol B. 66.1 g/mol C. 74.0 g/mol D. 81.4 g/mol Before After Before After Before After None of these options would occur

Your preview ends here

Eager to read complete document? Join bartleby learn and gain access to the full version

Access to all documents
Unlimited textbook solutions
24/7 expert homework help

Page 2 of 5 Exam 3 CHEMISTRY 1113 6. Methane, CH 4 ( g ), reacts with steam to give synthesis gas, a mixture of carbon monoxide and hydrogen, which is used as starting material for the synthesis of a number of organic and inorganic compounds. CH 4 ( g ) + H 2 O( g ) → CO( g ) + H 2 ( g ) [ unbalanced ] What mass of hydrogen gas is formed if 275 L of methane (measured at STP) is converted to synthesis gas? A. 74.4 g B. 37.1 g C. 49.4 g D. 24.7 g 7. Oxygen gas can be produced by the electrolysis of water. If a sample of oxygen gas is collected over water in this way at a temperature of 300. K in a container with a volume of 2.00 liters and the total pressure in the container is 780. torr, how many moles of oxygen gas were collected? The vapor pressure of water at 300 K is 24 torr. A. 63.4 mol B. 61.5 mol C. 0.0834 mol D. 0.0809 mol 8. A sample of gaseous helium is heated from 298 K to 373 K. Does the average de Broglie wavelength of the helium atoms change upon heating? If so, at which temperature do the helium atoms have a longer average de Broglie wavelength? A. 298 K B. 373 K C. The wavelengths do not change as the temperature changes. D. Helium atoms are not waves and so they do not have a wavelength. 9. An unknown gas effuses at a rate that is 0.895 times that of O 2 at the same temperature. What is the identity of the unknown gas? A. He B. Ne C. Ar D. Br 2 10. Which of the following colors has photons of the highest frequency? A. Green B. Red C. Yellow D. Blue

CHEMISTRY 1113 Exam 3 Page 3 of 5 11. Consider an Apple iPhone which operates at a frequency of 848 MHz. Calculate the wavelength corresponding to this frequency. (Hint: 1 MHz = 1 x 10 6 Hz) A. 0.354 m B. 3.75 x 10 13 m C. 2.83 m D. 1.98 x 10 4 m 12. A photon has 7.20 x 10 -19 J. Calculate the wavelength of light with this energy. A. 115 nm B. 934 nm C. 276 nm D. 382 nm 13. Choose the false statement regarding electronic transitions. A. A transition from n = 2 → n = 3 represents an absorption while a transition from n = 4 → n = 1 represents an emission. B. It is possible for a transition to fall in the IR region of the electromagnetic spectrum. C. Ground state absorptions start at n = 1. D. The energy of a photon absorbed is always greater than the energy of a photon emitted. 14. Which of the following emissions in the Bohr model of the H-atom would correspond to the highest frequency? A. n = 5 → n = 3 B. n = 3 → n = 4 C. n = 2 → n = 5 D. n = 3 → n = 1 15. The electron in a hydrogen atom undergoes a transition from n = 2 to n = 4 by interacting with a photon. What is the frequency of the photon, and is the photon absorbed or emitted? A. 2.056 × 10 6 s − 1 , emitted B. 2.742 × 10 6 s − 1 , absorbed C. 6.169 × 10 14 s − 1 , absorbed D. 8.226 × 10 14 s − 1 , emitted

Page 4 of 5 Exam 3 CHEMISTRY 1113 16. Which of the following statements regarding quantum numbers is incorrect ? A. The maximum value of l is always 1 less than n. B. The orientation of each subshell/sublevel is given by m l . C. Each orbital can hold a maximum of 2 electrons. D. n can take on any integer values starting with zero. 17. Choose the false statement regarding the orbital shown to the right. A. A possible value of n could be 2. B. A possible value of m l could be -2. C. The value of l must be 1. D. The maximum number of electrons this subshell can hold is 6. 18. An electron is described with the following four quantum numbers: n = 4, l = 2, m l = -2, m s = +1/2. Which sublevel does the electron reside in? A. s B. p C. d D. f 19. Which is the incorrect ground state condensed (noble gas) electron configuration for the element shown? A. Ba: [Xe] 6s 2 B. Br: [Ar] 4s 2 4d 10 4p 5 C. Cu: [Ar] 4s 1 3d 10 D. P: [Ne] 3s 2 3p 3 20. Choose the orbital diagram that correctly depicts the ground state valence electrons in an oxygen atom. A. C. B. D.

Your preview ends here

Eager to read complete document? Join bartleby learn and gain access to the full version

Access to all documents
Unlimited textbook solutions
24/7 expert homework help

CHEMISTRY 1113 Exam 3 Page 5 of 5 21. How many unpaired electrons are present in the d subshell of Ni 2+ ? A. 0 B. 2 C. 4 D. 8 22. How many valence and core electrons does the element chromium have? A. Valence = 6 Core = 18 B. Valence = 5 Core = 19 C. Valence = 1 Core = 23 D. Valence = 18 Core = 6 23. Consider lithium (Li) and beryllium (Be); which has the higher shielding constant and effective nuclear charge? A. Li has the higher shielding constant but Be has the higher effective nuclear charge. B. Li has the higher shielding constant and the higher effective nuclear charge. C. Be has the higher shielding constant and the higher effective nuclear charge. D. Be has the higher shielding constant but Li has the higher effective nuclear charge. 24. Arrange the following ions in order of increasing (smallest to largest) ionic radius: Cl - , Mg 2+ , Na + A. Cl - < Mg 2+ < Na + B. Mg +2 < Na + < Cl - C. Na + = Mg 2+ < Cl - D. Cl - < Na + = Mg 2+ 25. Consider the halogens: fluorine, chlorine, bromine, and iodine. Which element has the largest first ionization energy? A. Fluorine B. Chlorine C. Bromine D. Iodine