Intermolecular Forces

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2. Of the alcohols tested 1-Butanol was found to contain the strongest intermolecular forces (IMF) of attraction, with Methanol containing the weakest. It was discovered through experimentation that Methanol induced the highest ?T of all alcohols tested, and that conversely 1-Butanol induced the lowest ?T. The atomic structure of all four alcohols is very similar, as starting with 1-Butanol a CH2 group is lost as you move from 1-Butanol to 1-Propanol to Ethanol and then again to Methanol. Each structure is fairly linear and contains an H-bond with Oxygen, so the real change is found in the loss of the CH2 group, this lowers the liquid’s Molecular Mass, thus lowering the London forces as you move from 1-Butanol through
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An examination of the structures of the four alcohols revealed weakening IMF moving from 1-Butanol, to 1-Propanol, then Ethanol, and finally Methanol and experimentally the ?T increased in exactly that same order among those four alcohol samples (see Figure 1), providing evidence that since 1-Butanol had the lowest ?T, it therefore has the highest level of IMF (among the sampled alcohols), and conversely Methanol with it’s very large ?T (among the four) has the weakest IMF.

3. Of the two alkane liquids studied n-Hexane was determined to have the stronger IMF of attraction by virtue of its experimentally determined lower ?T. Conversely n-Pentane has weaker IMF of attraction due to its larger ?T. As explained at length above, this is because it takes more energy to excite a molecule in liquid to leave (vaporize or become gaseous), when there are stronger IMF of attraction holding the molecules together in liquid form.

4. n-Pentane and 1-Butanol have similar molecular weights, as well as fairly linear structures. This leads to them both having roughly similar London forces. However the 1-Butanol is packing a Hydroxyl group that the n-Pentane lacks, so when 1-Butanol is found experimentally to have a much lower ?T than n-Pentane, it is because it has much higher IMF of attraction due to Hydrogen Bonding compared to the n-Pentane. It also benefits from dipole-dipole forces due to its polarity as a molecule.

5. Water had the lowest