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quiz4A_solutions

# quiz4A_solutions - 3 YORK UNIVERSITY NAME b FW 2009 SC/CHEM...

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Unformatted text preview: 3 YORK UNIVERSITY NAME: b FW 2009 SC/CHEM 1000 3.0 A Student Number Quiz No. 4 November 26 2009 m R = 8.314472 JK'lmol'l = 0.0820574 L atm K" mor' 0°C = 273.15 K 1 standard atmosphere = 1.013 x 105 Pa = 760 torr (mm Hg) Avogadro’s number NA = 6.02214199x1023 molecules mol" Atomic masses: carbon 12.011, oxygen 15.9994, hydrogen 1.0079, argon 39.948, nitrogen 14.0067. The last page is a periodic table. It can be removed. ALL FINAL ANSWERS MUST BE WRITTEN IN INK MARKS [5] 1. 925 J are required to vaporize 1 g of ethanol (C2H5OH, MM=46.069 g mol") at its normal boiling point of 78.4 °C. What is the boiling point of ethanol in Boulder, Colorado when the atmospheric pressure is 640.1 Torr? Give your answer in °C. 5141/37? : 4:12—36:20“; 2.. any ; 3,15 4 —_—_ 4z-éIKTma/"' x-lmuo (awake : 337-6 K. I MW 1:: é40-(TM 77;; 7. _ .L. ’1 P. ft ’” ‘ A £404>= —M ,L ——_L.. > 77;: 8'3th 7..., 3576 73/ —= 34—7-5 K 743% \l FW 09 SC/CHEM 1000 3.0 A Page 2 . Quiz No. 4 [8] 2. Describe the bonding of the central atom in the following molecules in terms of hybrid orbitals. Indicate the shape of each molecule. Tetrachloroallene C12C=C=CC12. W MM 5,7 a zo’bmxo 1;. F --§ 277" 5% W [F5 (Iodine is the central atom). .Ezfr-E' Mew/7W” : /” Fl '. \‘c/ PC15 (Phosporus is the central atom). (’Z—ll '— 3 - / ‘ (my/1‘ i7ch 200‘ *W5W‘“; , \, ,/ on \C, K OClz (Oxygen is the central atom) a /\ ,_ L 3 ‘ M0 \C(-0-'C(l g/ 9M / ” W. FW 09 SC/CHEM 1000 3.0 A Page 3 _ Quiz No. 4 [7] 3. The Phase Diagram for He is shown below. Note that He I and He II are liquid phases. What phases of He are possible at 1 atrn and 300 K? W“? Estimate the normal boiling point of liquid helium from the ﬁgure. W Jamal M 4’4" Mark any Triple Points on the diagram with a “T”. What is the “7” pointing to? Mai/Pi Suppose you perform the following experiment. You start with He at equilibrium at 1 K and latm. You keep the pressure constant and raise the temperature to 2 K. Next you raise the pressure to 40 atrn. Describe what happens to the phases of He from the beginning of the experiment and while the experiment is being performed. g: e e A a B .3 C, 14—95 W [+6.71 \ FW 09 SC/CHEM 1000 3.0 A , Quiz No. 4 [10] 5. Page 4 List ethanol (C2H50H), propane (C3H8) and n-pentane (C5H12) in order of increasing boiling point. Brieﬂy explain your reasoning Why is diamond a good insulator whereas graphite is a good conductor? all WbMMS/Qj Explain why some molecules containing highly electronegative atoms are polar and some are not. d9.” (7.1/6, 4;,7pﬂm1pi‘ Mm “ ” Sketch an energy level diagram showing the unhybridized “s” and p orbitals in carbon. Beside this on the same energy scale, show the “spz” hybrid orbitals and any remaining orbitals. Show the electrons as arrows in these orbitals. 4 ,_ .:L 2. Energy 7‘? — 1— .LJ— 1. 5‘in P i 5 'll/ Unhybridized Hybridized Why is a sigma (a) bond stronger than a pi (7r) bond? gage/g4, may, [MFAMWMW m 59:4) THE END ...
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quiz4A_solutions - 3 YORK UNIVERSITY NAME b FW 2009 SC/CHEM...

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