Oil and Water Experiment Question

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SUMMARY

The forum discussion centers on a thermodynamics experiment involving the behavior of ice, water, and oil. The experiment aims to demonstrate that ice floats on oil but sinks as it melts into water. The user is facing challenges with water droplets refreezing at the bottom of a glass cylinder filled with vegetable oil, primarily due to surface tension and insufficient cooling. Suggestions include using dry ice for freezing and considering an intermediary medium to prevent water from sticking to the glass.

PREREQUISITES
  • Understanding of thermodynamic principles related to phase changes
  • Knowledge of fluid dynamics, particularly surface tension
  • Experience with experimental setups involving temperature control
  • Familiarity with materials like vegetable oil and dry ice
NEXT STEPS
  • Research methods for manipulating surface tension in liquids
  • Explore the properties and applications of dry ice in cooling experiments
  • Investigate alternative mediums to reduce adhesion between water and glass
  • Learn about capturing and presenting scientific experiments on video
USEFUL FOR

This discussion is beneficial for students in thermodynamics, educators seeking engaging experiments, and anyone interested in demonstrating principles of fluid dynamics and phase changes in a classroom setting.

FlashFry
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Hey everybody, I am currently in the process of coming up with a neat experiment for my thermodynamics class and I ran into some trouble. In my thermo class we were discuss phases, and separations and such, and I thought it would be cool to show how ice is less dense than oil and will float, but as it melts into water it will sink through an oil medium.

I am so far successful in recreating the melting part, however, I wanted to add something to this. I wanted to have the water droplet at the bottom of the oil medium refreeze and rise to the top (sort of like a reverse lava lamp).

My design is something like a foot tall glass cylinder, filled with vegetable oil. I let some ice float of on top and slowly melt. At the bottom of the cylinder, I have it sitting in an ice bath with salted water (attempting to get the temp < 0c). Unfortunately it is not working...

After doing some research I learned there can be issues with the water surface tension and sticking to the glass. I've also been having trouble getting the bottom of the glass cold enough to refreeze the droplets. I am hoping to get this to be a continuous process to show off to my class. After some brainstorming I was thinking of including another medium between the oil and glass to allow the water to sit without sticking, I might using dish soap... As for the freezing, I was thinking dry ice.

Any help or other ideas for showing off these cool thermodynamic principle would be greatly appreciated, thank you for your time!
 
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Dish soap is soluble in water so I don't think it would work. Dry ice *might* work, you have to tie it to a rock and drop it in, but the bubbles could give you trouble.

My recommendation is to put the entire thing in a freezer and capture it on video, then bring a flash drive to class with the file and play it over a projector if you have one available.
 

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