Chem%20161-2008%20final%20exam%20%2B%20answers

Chem%20161-2008%20final%20exam%20%2B%20answers - Chem...

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1 Chem 161-2008 Final exam Hill, Petrucci et al. Chapter 5 - Gases Kinetic molecular theory/Effusion and Diffusion/Real gases 1. Which of the following is inconsistent with the Kinetic-Molecular Model of gases? A. Gases consist of tiny particles in constant, random motion. B. The average kinetic energy of the particles of a gas is directly proportional to the temperature. C . Attractive and repulsive forces between gas particles are strong and must be included in the calculation of pressure. D. Collisions between particles or between gas particles and the walls results in no loss of kinetic energy. E. The volume of gas particles is insignificant in comparison to the volume of the container. A. Consistent. Gases do consist of tiny particles in constant, random motion. B. Consistent. (KE) avg = (3/2)RT C. Inconsistent. The Kinetic-Molecular Theory is for ideal gases, in which there are no forces between molecules. For real gases there are attractive and repulsive forces (I’m not certain of repulsive forces) between gas particles which may be strong and must be included in the calculation of pressure. D. Consistent. Although individual molecules may lose or gain kinetic energy when they collide with another molecule, the total kinetic energy doesn’t change; i.e., if one molecule slows down due to a collision with another molecule, the molecule it collides with speeds up. E. Consistent. The volume of gas particles is insignificant in comparison to the volume of the container. C. Attractive and repulsive forces between gas particles are strong and must be included in the calculation of pressure. Chem 161-2008 Final exam Hill, Petrucci et al. Chapter 2 - Atoms, Molecules, and Ions Nature of the atom (protons, neutrons, electons, symbols, isotopes, etc.) 2. How many protons, electrons and neutrons are in the 47 Ti 2+ ion? protons electrons neutrons A 22 22 23 B 20 22 25 C 22 20 25 D 22 24 25 E 25 20 22
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2 The atomic number for titanium is 22. Therefore, it has 22 protons. 47 is the mass number; therefore this titanium isotope contains 25 neutrons. Since the charge is 2+, then titanium has two more protons than electrons; therefore it has 20 electrons. C. Protons: 22; electrons: 20; neutrons: 25. Chem 161-2008 Final exam Hill, Petrucci et al. Chapter 3 – Stoichiometry: Chemical Calculations Reaction stoichiometry 3. A 1.80 g sample of barium chloride hydrate, BaCl 2 •xH 2 O is treated with excess sulfuric acid, forming a BaSO 4 precipitate which has a mass of 1.72g. Calculate the value of x. A. 1 B . 2 C. 3 D. 5 E. 7 BaCl 2 •xH 2 O + H 2 SO 4 BaSO 4 + 2HCl + xH 2 O 1.80g XS 1.72g Plan: All of the Ba 2+ in BaSO 4 comes from BaCl 2 . g BaSO 4 molBaSO 4 molBa in BaCl 2 gBa gH 2 O molH 2 O empirical formula MW BaSO 4 = 137.33 + 32.065 + 4x16.00 = 233.40g/mol MW BaCl 2 = 137.33 + 2x35.45 = 208.23 g/mol 1.72gBaSO 4 x (1molBaSO 4 /233.40gBaSO 4 ) x (1molBa [from BaCl 2 •xH 2 O]/1molBaSO 4 ) x 137.33gBa/mol Ba = 1.012g Ba in BaCl
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This note was uploaded on 03/08/2011 for the course CHEM 161 taught by Professor Vacillian during the Fall '08 term at Rutgers.

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Chem%20161-2008%20final%20exam%20%2B%20answers - Chem...

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