Embedded Files
Alcohol, Water and Oil - Effect on Skin Temps?
Alcohol, Water and Oil - Effect on Skin Temps?
Suppose you were to rub an alcohol wipe, hand sanitizer, soap and water or oil to wash your hands. As they evaporate, how do your hands feel?
70% Alcohol
50-70% Alcohol
Water
Oil
Investigating Evaporation - How can we quantify evaporation's effects on the body?
Using a simple model of an evaporating liquid, we will focus on data collection, graph interpretation and identifying limitations in our experimentation.
Additionally, we will create a list of questions of possible extensions of this simple investigation.
Intermolecular Forces:
Intermolecular Forces:
The amount of "stick togetherness" is important in the interpretation of the various properties listed to the right.
NO CHEMICAL REACTIONS are involved with IMF's however the processes are determined by the characteristics of the molecules.
General Resources:
Properties Affected by Intermolecular Forces:
Viscosity - How liquids flow
Solubility - How much will dissolve?
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.
Exploring a Property affected by IMFs
Exploring a Property affected by IMFs
Plan and conduct an investigation to gather evidence to compare the structure of substances at the bulk scale to infer the strength of electrical forces between particles.
Choose a property listed above, research / learn how IMFs affect that particular property. Explore how your experiment will affect your chosen property.
Students describe the phenomenon under investigation, which includes the following idea: the relationship between the measurable properties (listed above) of a substance and the strength of the electrical forces between the particles of the substance.
2. You will be creating an experiment to COMPARE different data sets. In the Evaporation Exploration, we used three different liquids (water, ethanol and acetone), however we could have changed the concentration of the acetone or ethanol to determine evaporation. How can you use the data collected to COMPARE the evaporation rate (volatility) of each liquid?
Students develop an investigation plan and describe the data that will be collected and the evidence to be derived from the data, including bulk properties of a substance (e.g., melting point and boiling point, volatility, surface tension) that would allow inferences to be made about the strength of electrical forces (IMFs) between particles.
3. You will need to include an explanation of WHY you chose to different substances (different molecules or different concentrations) to experiment with. Why do you think changing your independent variable will have an impact on the dependent variable?
4. How will you collect the enough data so that you can make a solid conclusion?
i. A rationale for the choice of substances to compare and a description of the composition of those substances at the atomic molecular scale.
ii. A description of how the data will be collected, the number of trials, and the experimental set up and equipment required.
5. Following a similar process when you collect the heart rate data, answer the following:
Can you draw a conclusion from the data you collected?
Did you collect the 'right' data, enough data, or limit the outside variables enough to provide evidence for your conclusion?
If you were to repeat the experiment, what changes you you make to your data collection process?
If you were to conduct a followup experiment, outline the process you would you explore?
Students evaluate their investigation, including evaluation of:
i. Assessing the accuracy and precision of the data collected, as well as the limitations of the investigation; and
ii. The ability of the data to provide the evidence required.
Students propose refinements to the plan to produce more accurate, precise, and useful data.
Surface Tension v. Viscosity C.E.R.
Surface Tension v. Viscosity C.E.R.
Make a COPY HERE
Using your knowledge of IMFs, create a CER describing the relationships between IMFs, surface tension and viscosity. (What do your results show and how can you explain them using IMFs?)
Create a series of graphs to illustrate the relationships between Viscosity to Surface Tension.
Improvements to the experimentation process:
If you were to repeat the experiment, how would you change the procedure(s) to obtain.
How does your data compare to other research? (Is there information on the web that you can compare your results to? If so, compare them.)
Terms you may want to include:
Terms you may want to include:
Polar Molecules
Non-Polar Molecules
Hydrogen Bonding
Intermolecular Forces
Viscosity
Surface Tension
Molecular Interaction
Control Variables
Independent variable
Dependent variable
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?
Page updated
Google Sites
Report abuse