Name:_____________________________________________________________________________________________________________
Hydrogen Bonding Lab (Unit 6.2-6.3)
PRELAB QUESTIONS
1. Name the three main intermolecular forces and briefly describe each.
2. What factors help determine a substance’s boiling point?
3. What three elements other then hydrogen do you need for hydrogen bonding?
4. Fill in the following table:
Substance
Formula
Ethanol
C3H5OH
1-propanol
C3H7OH
1-butanol
C4H9OH
n-pentane
C5H12
methanol
CH3OH
n-heptane
C7H16
Structural Formula
Molecular Weight
(amu)
Strongest IMF
Name:_____________________________________________________________________________________________________________
PROCEDURE
1. Obtain a TIN-Spire Calculator, and 1 temperature probe.
2. Remove the “top hat” from the calculator and plug in the temperature probe into the top of the calculator
3. Turn on the calculator. If the DataQuest window doesn’t automatically appear, select the green icon on the bottom
right corner of the home screen (Vernier DataQuest).
4. A temperature reading should appear automatically. If it does not, please see me.
5. Set up the probe by pushing the menu button. Then select Experiment (#1). Then select collection setup (#8).
6. Change the first option from rate (samples/second) to interval (seconds/ sample).
7. For interval enter : 3 and for duration enter: 240. Then, hit OK.
8. Wrap your temperature probe with a piece of filter paper secured by small rubberband. Roll the filter paper around
the probe tip in the shape of a cylinder. Hint: First slip the rubber band up on the probe, wrap the paper around the
probe, and then finally slip the rubber band over the wrapped paper. The paper should be even with the probe end.
9. Place your probe in your assigned. Make sure the container does not tip over.
10. Prepare a piece of tape, about 10-cm long, to be used to tape the probe in position during Step 11.
11. After the probes have been in the liquids for at least 45 seconds, press the green arrow on the bottom of the
calculator screen to begin data collection. Monitor the temperature for 15 seconds to establish the initial temperature
of each liquid. Then, remove the probe from the liquid and tape it so the probe tip extend 5 cm over the edge of the
table top.
12. When data collection is complete after 4.0 minutes, a graph should automatically appear. Use the tabs in the top left
corner to switch to the data table view.
13. Use the up and down arrow to examine the data points for your substance. Based on your data, determine the
maximum temperature, t2, and minimum temperature, t1. Record t2 and t1 for your substance.
14. For your liquid, subtract the minimum temperature from the maximum temperature to determine ∆t, the
temperature change during evaporation. Share your information with the rest of the class.
15. Roll the rubber band up the probe shaft and dispose of the filter paper as directed by your teacher.
16. Based on the ∆t values you have obtained for all four substances, plus information in the Pre-Lab exercise, predict
the ∆t values for methanol and n-hexane. Compare the hydrogen-bonding capability and molecular weight of methanol
and n-heptane to those of the previous four liquids. Record your predicted ∆t, then explain how you arrived at this
answer in the space provided.
17. Repeat Steps 11-15 using methanol or n-heptane. This will help you support or refute your prediction from Step 17.
Name:_____________________________________________________________________________________________________________
DATA TABLES
Your Substance
t2 (high temperature) °C
Substance
Trial 1 ∆t
Trial 2 ∆t
t1 (low temperature) °C
Trial 3 ∆t
∆t (t2-t1) °C
Average ∆t
ethanol
1-propanol
1-butanol
n-pentane
methanol
n-heptane
PREDICTIONS
Substance
∆t
Reasoning
methanol
n-heptane
POST LAB QUESTIONS
1. Two of the liquids, n-pentane and 1-butanol, had nearly the same molecular weights, but significantly different ∆t
values. Explain the difference in ∆t values of these substances, based on their intermolecular forces.
2. Which of the alcohols studied has the strongest intermolecular forces of attraction? Which has the weakest
intermolecular forces? Explain using the results of this experiment.
3. Which of the alkanes studied has the strongest intermolecular forces of attraction? Which has the weakest
intermolecular forces? Explain using the results of this experiment.