Category Medium Section 113 108 Iron crystallizes in a body centered cubic unit

Category medium section 113 108 iron crystallizes in

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Category: Medium Section: 11.3 108. Iron crystallizes in a body-centered cubic unit. The edge of this cell is 287 pm. Calculate the density of iron. Ans: 7.86 g/cm3Category: Medium Section: 11.4 109. Copper crystallizes in a face-centered cubic unit cell. The density of copper is 8.94 g/cm3. Calculate the length of the edge of the unit cell in pm. Ans: 361 pm Category: Medium Section: 11.4 110. Of the given pair of compounds, which would have the higher boiling point? C3H8or CH3OCH3111. Of the given pair of compounds, which would have the higher boiling point? 112. Of the given pair of compounds, which would have the higher boiling point? 113. Of the given pair of compounds, which would have the higher boiling point? CH3Cl or CH4Ans: CH3Cl Category: Medium Section: 11.2 114. Of the given pair of compounds, which would have the higher boiling point?
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115. Osmium tetroxide, OsO4, is a soft crystal that melts at 40°C. The liquid does not conduct electricity. What kind of crystal is this? 116. Boron nitride, BN3, melts at approximately at 3,000°C under high pressure. This materal is almost as hard as diamond. What kind of crystal is this? 117. Crystals of elemental sulfur are easily crushed, and melt at 113°C. Liquid sulfur does not conduct electricity. What kind of crystal is this? Ans: Molecular crystal Category: Medium Section: 11.6 118. Magnesium oxide, MgO, melts at 2,800°C and is very hard. The liquid conducts electricity very well. What kind of crystal is this? 119. Sodium iodide, NaI, melts at 651°C. In its liquid state NaI conducts electricity. What kind of crystal is this? 120. Which is expected to have a higher boiling point, C8H18or C4H10? 121. Which is expected to have a higher boiling point, C5H12or C(CH3)4? Ans: C5H12Category: Medium Section: 11.2 122. Methane has a heat of fusion of 0.84 kJ/mol and a heat of vaporization of 9.2 kJ/mol. Estimate the value for the heat of sublimation. Ans: 10.0 kJ/mol Category: Medium Section: 11.8 123. Ethanol and dimethyl ether have the same molecular formula, C2H6O. Ethanol boils at 78.4°C. Dimethyl ether boils at –23.7°C. Their structural formulas are, respectively, CH3CH2OH and CH3OCH3. Explain why the boiling point of the ether is so much lower than the boiling point of ethanol. Ans: Ethanol is a polar molecule that has stronger attractive forces, hydrogen bonding in particular, than ether, which is slightly polar but cannot form hydrogen bonds.
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  • Spring '10
  • Shaklovich
  • Vapor pressure, Diethyl ether, Medium Section, CHCl3

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