answer Key Mid-term Exam corr II2005

answer Key Mid-term Exam corr II2005 - 1-5.Two beakers, A...

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Unformatted text preview: 1-5.Two beakers, A and B, are placed in a bell jar at 298 K as illustrated below. Beaker A contains 4.00 molof pure diethyl ether which has a vapor pressure of 400 Torrand beaker B contains 2.00 molof pure pentane which has a vapor pressure of 700 Torr. Diethyl ether and pentane are miscible liquids. The bell jar is left undisturbed until the composition of the liquids in A and B no longer changes.1.The initial mole fraction of A in the vapor of the bell jar at the beginningof the period is (a)0.400 ANSWER (c) 0.364(b)0.700 (c)0.364 (d)0.636 (e)1.000 2.The initial mole fraction of B in the vapor of the bell jar at the beginningof the period is (a)0.400 ANSWER (d) 0.636(b)0.700 (c)0.364 (d)0.636 (e)1.000 3.The mole fraction of diethyl ether in the liquid in beaker A at the endof the waiting period is (a)0.500 ANSWER (b) 0.667(b)0.667 (c)1.000 (d)0.333 (e)0.400 4.The mole fraction of pentane in the liquid in beaker B at the endof the waiting period is (a)0.500 ANSWER (d) 0.333(b)0.667 (c)1.000 (d)0.333 (e)0.466 5.The mole fraction of pentane in the vapor in the bell jar at the endof the waiting period is (a)0.500 ANSWER (e) 0.466(b)0.667 (c)1.000 (d)0.333 (e)0.466 6.When one molof carbon dioxide gas is dissolved in water the change in the entropy, S, is (a)Positive ANSWER (b) negative(b)negative (c)zero (d)not predictable (e)3/2 R 7.When a sparingly soluble ionic compound is mixed with pure water the change in the gibbs free energy for dissolution of the compound is (a)Positive ANSWER (b) negative(b)negative (c)zero (d)not predictable (e)5/2 RT 8.The solubility of oxygen in water (a)decreases with increasing temperature ANSWER (a) decreases(b)increases with increasing temperature (c)is not influenced by temperature (d)temperature dependence cannot be predicted (e)is 3/2R at 298 K 9-14. Various types of solids are listed below. For questions 9-12 choose the type of solid that best fits the description of the material that is given. (a) covalent network (b) metal (c) ionic lattice (d) semiconductor (e) molecular solid 9. A solid white material that is an insulator as a solid but becomes a conductor when it is melted to a liquid. ANSWER (c) ionic lattice 10. A solid white material that is an insulator and melts just above room temperature and remains an insulator. ANSWER (e) molecular solid 11. Pure elemental Si. Pure elemental Si....
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This note was uploaded on 03/20/2010 for the course CHEM 1C taught by Professor Hooker during the Spring '06 term at UCSB.

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answer Key Mid-term Exam corr II2005 - 1-5.Two beakers, A...

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