CH 101 Exam 3 Spring 2012

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Community College of Baltimore County *

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101

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Chemistry

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Dec 6, 2023

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docx

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7

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CH 101 Ellis Exam 3 Name ______________________________________ Phase diagram for problems 27-29; Periodic table; Table 4.1Sol. Rules p. 149; Table 6.4 p. 241; Table 6.5 p. 258 Problems. 1. Larry the kitten runs at 8.0 m/s around the Ellis house. Larry is planning on weighing at least 7.50 kg when he grows up. Larry would like to know: what will his kinetic energy be when he is an adult cat? (5 points) 2. The main active ingredient in dental whitening products is often the liquid hydrogen peroxide, H 2 O 2 . Given time, it will decompose to water and oxygen (hence the need to use the whitener promptly after purchase). It is synthesized from a reaction of hydrogen gas with oxygen gas: H 2 (g) + O 2 (g) H 2 O 2 (l) Determine the enthalpy change for this synthesis using the following information. Show your work. (8 points) H 2 O 2 (l) H 2 O (l) + ½ O 2 (g) ;∆H = -98.0 kJ 2 H 2 (g) + O 2 (g) 2 H 2 O (l) ; ∆H = -571.6 kJ
3. Quantum Mechanics problems. Do not use a noble gas abbreviation in your answer-if you do, you will not receive credit for that answe r. Point value varies. a. Give the electron configuration for the ground state of selenium. (5 points) b. Write the orbital diagram for the ground state of cobalt. Show all orbitals. (5 points) c. Give the four quantum numbers for the last electron in phosphorus using the Aufbau Principle and Hund’s rule. (4 points) d. Would the electron in question “c” be a core electron or a valence electron (1 point)? Circle your answer. e. Give the four quantum numbers for the last electron placed in iron using the Aufbau Principle and Hund’s rule. (4 points) f. Would the electron in question “e” be a core electron or a valence electron (1 point)? Circle your answer.
4. a. Consider the following exothermic reaction: one mole of liquid acetone (C 3 H 6 O) combusts with oxygen gas to yield gaseous carbon dioxide and steam (gaseous water). The enthalpy change for this reaction is 1790 kJ. Write the balanced thermochemical equation for this reaction. (5 points) 4 b. This is a precipitation neutralization oxidation-reduction reaction. (2 points) Circle your answer. 5. Write the balanced thermochemical equation for the formation of sodium carbonate from its elements in their standard states. (5 points)
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