IMF - Experimentation

1. Khalid: Since we have that awesome lab, maybe we could design an experiment to actually quantify the strength of intermolecular forces in different liquids.

2. Fatima: That's a great idea, Khalid! We could compare things like water, ethanol, and glycerol. We could measure their boiling points precisely using those digital thermometers and distillation apparatus. That would give us a direct measure of the energy needed to overcome the intermolecular forces.

3. Ayah: And we could also investigate viscosity. We could use a viscometer to measure the time it takes for a specific volume of each liquid to flow through a capillary tube. We could even change the temperature and see how that affects the viscosity.

4. Khalid: Instead of the Du Noüy ring, we could try the capillary rise method to measure surface tension. We could use those thin glass tubes and measure how high each liquid climbs up the tube. The stronger the intermolecular forces, the higher the liquid should rise, right?

5. Fatima: Exactly! And we can use the travelling microscope to get a really accurate measurement of the height. We should also make sure the tubes are clean and that we repeat the experiment a few times to get consistent results.

6. Ayah: And to make sure our results are reliable, we should repeat each measurement multiple times and calculate the average. We could also compare our results to published data to see if they're consistent.

7. Khalid: We should also consider the potential sources of error in our experiment, like variations in temperature or the diameter of the capillary tubes. We need to control those variables as much as possible.

8. Ayah: We could even try mixing different liquids in various ratios and see how that affects the intermolecular forces. Maybe we could create a mixture with specific properties, like a new type of solvent or lubricant.

9. Fatima: This is going to be so cool! We could present our findings to the class and maybe even write a report for the school science journal.

10. Ayah: I'm really excited about this! It's a chance to apply what we've learned and contribute to scientific knowledge.

• Viscosity - How liquids flow

• Solubility - How much will dissolve?

• Adhesion/Cohesion - Sticking together or to others.

• Surface Tension - How much will it support?

• Vapor Pressure - What are the limits to evaporation?

• Melting Point - At what temperature does a solid turn to liquid (and v.v.).

• Boiling Point - At what temperature does a liquid turn to gas (and v.v.).

• Evaporation - Changing states without passing the boiling point. 

Evidence / Analysis of Data: 

• Table 1: Raw Data: Include a table for your Raw data (data collected directly from the lab)

• Table 2: Sample Calculations: Include one example of each type of calculation you performed. (Optional - Only necessary if doing a complex calculation)

• Table 3: Processed Data: After you have completed any calculations, the data should be presented here.

• Graph #1 - x: A graph of your processed data.

  • THIS IS THE EVIDENCE that you should refer to.

  • 2-3 sentences saying what this graph means.

Reasoning:

• Explains how and why EACH piece of evidence supports your claim.

• Interpretation of data gathered from observations, experience, or research materials.

• Include an explanation of the underlying science concept (IMFs and Polarity) that produced the evidence or data.

Goals: 

• Evaluates weaknesses and limitations.

  • Evaluation of Results - 

    • Were the measurements accurate (close to the true values) and precise (close to each other)?

    • Is your conclusion (claim) reasonable or not, based on your evidence?

    • Each comment needs to be supported with evidence from your data.

  • Limitations of Procedure - 

    • Focus on Design of experiment

      • Control Variables: What variables did you not control or forgot to control?

      • # of Trials: 

        • Did you collect enough trials to eliminate possible outliers?

      • Range of data: 

        • Did you collect data over the entire range of possibilities that your equipment allowed for?

        • Did you collect too much of a range? Beyond the limitations of your equipment. Did you max out your sensors/measuring device?

• Improving the Experiment:

  • From the list of Limitations above, suggest reasonable improvements to the design of the experiment to increase the reliability of your evidence.

  • Utilize a table as shown to the right

  • Note: do not say “Measurements could have been more accurate…” or “there was error in measurement.” Or “we could have worked harder/paid more attention.” Those are not valid evaluation statements and you are just wasting paper. 

  • Are there further experiments that can be performed or did the data suggest other avenues to explore?