Name IMF Unit Electrostatic Forces Liquids Draw the Lewis structure for each of the molecules and answer questions 1 4 which refer to this data table Molecule Formula CH4 Molecular Weight 16 g mol Boiling Point 161 C Methane Ethane C2 H6 30 g mol 88 7 C Hexane C6H14 86 g mol 68 7 C Octane C8H18 114 g mol 126 C Methanol CH3OH 32 g mol 64 7 C Ethanol CH3CH2OH 46 g mol 78 C Water H2 O 18 g mol 100 C Ethane di ol Ethylene Glycol CH2OHCH2OH 62 g mol 197 C Carbon Tetrachloride CCl4 77 C Revised SH 7 12 13 154 g mol Lewis Structure LaBrake Vanden Bout 2013 Name 1 Look at the table on previous page and comment on the correlation between the molecular weight and the boiling point As molecular weight increases the boiling point increases BUT the pattern is only followed only if you re looking at molecules with the same number of OH groups 2 Look at the Lewis structures of the molecules and comment on the correlation between the structure of the molecule and the boiling point The OH groups matter when determining boiling point The bigger more stretched out the molecule and or the greater number of lone pairs it has correlates to a higher boiling point 3 Comment on the correlation between the number of O H bonds and the boiling point The more OH groups the higher the boiling point see ethanol vs ethylene diol 4 From this data what factors would you predict affect the physical properties of liquids Molecular weight polarity and the degree of polarity 5 Study the graph below a What is the y axis What is the x axis Boiling Point Period on the Periodic Table b What is the trend in B P s of hydrides within a period of the periodic table As you move across a period boiling point increases c What is the trend in B P s for hydrides within a group In general as you move down a group boiling point increases d What is the trend within period 2 Within period 3 Period 2 is more dramatic Molecules with F O N attached to H do not follow the trends because they experience hydrogen bonding IMFs Period 3 follows the expected trends l Revised SH 7 12 13 LaBrake Vanden Bout 2013
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