CHM 2046L Intermolecular Forces Part 2: Attractive Forces of Hydrocarbons Data T
ID: 1082072 • Letter: C
Question
CHM 2046L Intermolecular Forces Part 2: Attractive Forces of Hydrocarbons Data Table: Number of Carbons Viscosity/Total IMFs (See Post-Lalb Substance State of matter C & H Only an One OH per CMethano 2 s e 6 Observations or Comments on the "C&H;" series, on the "one Oll per C" series, and comparisons of the two series: 0 Which of the two series (C&H;" or "one OH per C) seems to have greater IMFs? How did you reach that conclusion? (10 pt.) Within each series, does there seem to be any pattern to the strength of IMFs? If so, what is the pattern? (10 pt.)Explanation / Answer
1. Observations: We can observe in the "C&H" series, that as the number of C atoms increases from methane (1 C) to butane (with 4 C) the IMF increase by 6 i.e. there is an increment of 2 units per C added. In pentane with 5 C, the IMF is 12 again showing the increment of IMF by 2 per C added.
In"one OH per C" series, for methanol with 1 C the IMF is 14, for ethylene glycol with 2 C the IMF increases by 12 units i.e. a value of 26 units. For glycerol with 3 C, again there is an increment of 12 units for the 1 C added i.e. a value of 38 units.
Now we can see for "C&H" series, for methane with 1 C, the total IMF is 4 where as for "one OH per C" series, for methanol with 1 C the IMF is 14. So that means due to presence of OH group the IMF increase many times when compared to "C&H" series.
2. We can see clearly that the "one OH per C" series has more IMF because methane with 1 C has IMF 4 whereas methanol with 1 C and 1 OH has IMF 14. Also ethylene glycol (with 2 Cand 2 OH) has IMF of 26 whereas butane of C&H series with 4 C has IMF of 10 which is very less as compared to that of ethylene glycol of "one OH per C" series. This could be due to only vander waal forces of attraction in "C&H" compounds and additional presence of Hydrogen bonding (stronger IMF than vander waal forces) in the "one OH per C" substances.
3. As discussed in point 1 under observations, we can observe an increment of IMF of 2 units per C added in the "C&H" series in the lower end of the series. On the other hand in the "one OH per C" series there is an increment of 12 units of IMF per C added in the straight chain compounds given in the lower end of the series. We can observe that glucose which is a ring compound with 6 C doesn't show the regular gradation in IMF else it would have been 14+12*5=14+60=74 (considering an increment of 12 units IMF per C added). The actual IMF is 69 which is less than the expected value of 74 probably due to formation of ring structure resulting in less effective packing.