Why do liquids evaporate at different rates?
Section 1 As a member of Group 2, we were investigating why the liquids Ethanol, Propanol, Water, Pentane and Acetone evaporate at different rates. Methanol and Butanol were not liquids investigated by our group, but collectively as a class we were able to record averages of rates of evaporation.
Solvent
Molecular Formula
Boiling Point (C°)
Polar or Nonpolar
Intermolecular Force(s)
Lewis Dot
Structure
Methanol
CH4O
64.7
Polar
Hydrogen Bonding
Dipole-Dipole
London Dispersion
Ethanol
C2H6O
78.37
Polar
Hydrogen Bonding
Dipole-Dipole
London Dispersion
Propanol
C3H8O
97.0
Polar
Hydrogen Bonding
Dipole-Dipole
London Dispersion
Butanol
C4H10O
117.0
Polar
Hydrogen Bonding
Dipole-Dipole
London Dispersion
Water
H2O
99.98
Polar
Hydrogen Bonding
Dipole-Dipole
London Dispersion
Pentane
C5H12
36.1
Nonpolar
London Dispersion
Acetone
C3H6O
56.0
Polar
Dipole-Dipole
London Dispersion
We learned that vaporization is higher in molecules with weak intermolecular forces and the higher the boiling point the stronger the molecule. So in order from weakest to strongest, the evaporation rates of the liquids should go as follows: 1) Pentane, 2) Acetone, 3) Methanol, 4) Ethanol, 5) Propanol, 6) Water, and 7) Butanol.
Section 2 In order to perform the investigation, we had to first create a data table to record our results. The procedure went as followed:
1. Set-up the data collection program to collect data for 300 seconds.
2. Wrap the probe with chromatography paper and secure with a rubber band. Wrapped probes provide more uniform liquid amounts, and generally greater T values than bare probes.
3. Stand the probe in the liquid until the temperature reading is stable, hit start and collect data for 15 seconds to establish the initial temperature, Ti. Then remove the probe from the liquid.
4. Use the statistics function to find the minimum and the maximum temperature readings.
NOTE: The minimum temperature reading may occur before 300 seconds for some liquids.
This
Solvent
Molecular Formula
Boiling Point (C°)
Polar or Nonpolar
Intermolecular Force(s)
Lewis Dot
Structure
Methanol
CH4O
64.7
Polar
Hydrogen Bonding
Dipole-Dipole
London Dispersion
Ethanol
C2H6O
78.37
Polar
Hydrogen Bonding
Dipole-Dipole
London Dispersion
Propanol
C3H8O
97.0
Polar
Hydrogen Bonding
Dipole-Dipole
London Dispersion
Butanol
C4H10O
117.0
Polar
Hydrogen Bonding
Dipole-Dipole
London Dispersion
Water
H2O
99.98
Polar
Hydrogen Bonding
Dipole-Dipole
London Dispersion
Pentane
C5H12
36.1
Nonpolar
London Dispersion
Acetone
C3H6O
56.0
Polar
Dipole-Dipole
London Dispersion
We learned that vaporization is higher in molecules with weak intermolecular forces and the higher the boiling point the stronger the molecule. So in order from weakest to strongest, the evaporation rates of the liquids should go as follows: 1) Pentane, 2) Acetone, 3) Methanol, 4) Ethanol, 5) Propanol, 6) Water, and 7) Butanol.
Section 2 In order to perform the investigation, we had to first create a data table to record our results. The procedure went as followed:
1. Set-up the data collection program to collect data for 300 seconds.
2. Wrap the probe with chromatography paper and secure with a rubber band. Wrapped probes provide more uniform liquid amounts, and generally greater T values than bare probes.
3. Stand the probe in the liquid until the temperature reading is stable, hit start and collect data for 15 seconds to establish the initial temperature, Ti. Then remove the probe from the liquid.
4. Use the statistics function to find the minimum and the maximum temperature readings.
NOTE: The minimum temperature reading may occur before 300 seconds for some liquids.
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