Arasarathnam 1
Cedarbrae Collegiate Institute
Boiling Points and Intermolecular Forces Lab
Rajan Arasarathnam
SCH4U1
Mr. Singh
2024–03-08
Arasarathnam 1
1. What variables were measured, recorded, and/or manipulated in each part of this
investigation?
The variables that were measured were the water and the different alcohol. The beaker
was filled with exactly 250 ml of water for each test. The test tubes were filled with
approximately 5 ml each time for each type of alcohol (5 drops per tube).
Molecular Weight vs Boiling Point
Alcohol
Molecular Mass
Boiling Point
n-Propyl
60.09 g/mol
97°C
Isobutyl
74.12 g/mol
108°C
Ethyl
46.07 g/mol
78°C
Methanol Absolute
32.04 g/mol
65°C
2. Explain the graph of the molecules in terms of intermolecular forces.
The pattern seems to be that the heavier the molecule, the higher the boiling point. This
is due to the fact that heavier molecules have more electrons, thus resulting in greater polarity
and stronger intermolecular forces.
3. Why is there a difference in boiling point between propanol and isopropanol?
They have two slightly different chemical formulas. Isopropanol is C3H8O while propanol
is CH3CH2CH2OH. Essentially, the difference is the attached OH bond instead of a singular
oxygen atom. OH being a hydrogen bond makes the intermolecular forces of propanol stronger,
thus causing it to have a higher boiling point than isopropanol.
4. Explain these results in terms of intermolecular forces.
We know that intermolecular forces are stronger based on the number of electrons. Thus
CaH2 will have stronger intermolecular forces than MgH2 which will be stronger than BeH2
simply because of the higher number of electrons. That is why CaH2 has the highest boiling
point while BeH2 has the lowest.
5. Which solvent should you use? Think of a better solvent and explain why it would be better.
Out of the 3, you should use propanol as it has the lowest boiling point, thus evaporating
the quickest. I would use a solvent with a lower boiling point such as methanol since it would
evaporate even faster.