# 8 & 12 & 14 September Science 8 Summative Assessment Mixing Ethanol and Water

Today:

Select some aspect of mixing ethanol and water that you want to investigate further. Keep track of your procedure(s) and results. This will be the second part of your report. Please clear any ideas with Dr. F regarding safety and practicality.

If you have already embarked on a procedure where you are examining the behavior and density of various concentrations of ethanol and water (90% to 10%; 80% to 20%; 70% to 30% and so on), you may continue. Your part 1 and part 2 can be based on this process.

Some other ideas if you are having difficulty:

What happens if 50 ml of ethanol is added to 50 ml of a saturated salt solution? What do you expect? Why?

What happens if 50 ml of ethanol is added to 50 ml of a saturated sugar solution? What do you expect? Why?

What is the “loss of volume” if ethanol and water kept cold in an ice bath are used? What is the density of ethanol at that temperature? What is the density of water at that temperature?

Find out how the density of water changes with temperature. Start with 100 ml of very hot water. Find the mass. Let it sit on the balance and cool observing the mass and the volume. Have a second cylinder filled to 100 ml with the same hot water nearby. Insert a thermometer. Use this cylinder and hot water to monitor the temperature. Watch the time and take the temperature every minute as you monitor the mass and volume. Both cylinders should be fitted with stoppers.

You will have next Tuesday the 19th (a shortened class) to work on your report. The report will be due at the beginning of class on the 21st.

Begin working on a document or presentation for the parent-student-teacher conference:

## h) Discuss your learning habits. Respectful, Responsible, Collaborative, Perseverant.

On the 12th:

Select an explanation to test. Design and conduct the test. Clear design with Dr. F for safety and practicality.

If the explanation is “true,” then . . . should happen / appear /change in … way.

1. If the prediction is true, then the explanation is supported.
2. If the prediction is false, then the explanation is (may be) challenged. (In science it is good to rule out explanations that do not work.)
3. An explanation must be logical AND have corroborating evidence to be supported.
4. Good scientific explanations are testable, are based on cause and effect, account for the phenomena, and are generative–produce new ideas and directions for inquiry and may extend into other domains.

Next class:

Select some phenomenon you have observed related to the mixing of ethanol and water or some question that has occurred to you during our investigation of the mixing. Design a method for addressing your question. Clear design with Dr. F for safety and practicality. Conduct this second investigation.

Write a report in the specified format.

Attend to these points:

• Ethanol is flammable.
• Do not inhale vapors–we have exhaust fans on.
• Wear eye protection to prevent injury from splashes.
• Do not measure at the sinks or supply stations. Use beakers to take the amount of substance that you will need to your table.
• Be careful with glassware. Avoid spills and breakage.
• Make careful measurements.
• Measure temperature before you measure volume.
• Record (make notes) procedures–what you do;
• AND record (make notes) of what you see.
• Introduction (5 minutes)
• Step 1. Replicate the demonstration. (20 minutes)
• Step 2. Share your results. (5 minutes) (ask for permission to edit)
• Step 3. Develop an explanation. (15 minutes)
• Step 4. Share proposed explanations. (10 minutes)If you did not share in class, do so as soon as possible on the document.
• Step 5. Design investigation–1. Test(s) of explanation(s) offered in document above or another that you suspect. 2. Further investigation of some aspect of phenomena–mixing ethanol and water (carefully review the Assessment Project description below–see the sample report by a previous Science 8 class) (10 minutes)
• Step 6. Consult with Dr. F  and clean-up (10 minutes)
• During any time you are waiting–and before the next class–carefully review the Assessment Project description–below. Be sure to see the sample report by a previous Science 8 class.

8, 12, 14, 19 Sept. Due 21 Sept. at the beginning of class.

Molecular diagrams of ethanol and water:

https://en.wikipedia.org/wiki/Ethanol#/media/File:Ethanol-3D-balls.png

https://en.wikipedia.org/wiki/Properties_of_water#/media/File:Water-3D-balls.png