Observing "Frictionless" Phenomenon with Acetone in Lab

[enroger]

The other day I was working in the lab and observed a very interesting fluid dynamic thing in a beaker:

I was cooking acetone on a hot plate to clean a sample, then I see little bubbles on the surface bouncing around. The strange thing is that those bubbles act EXACTLY like a ball on a frictionless surface! They never decelerate (or accelerate for that matter), just travel on a straight line, when ever they hit a obstacle (beaker wall/ sample) they will be bounced back like a tennis ball hitting a wall.

That bubbles don't slow down due to friction really bug me. I guess the evaporation provides energy for the motion in a reinforced kind of way to maintain the pattern. Maybe it count as a soliton? And there should be no convection when this happens.

I tried to repeat this with 2-propenal, nothing like that happens. With Aceton it works every time. Maybe Acetone has the exact right viscosity/evaporation rate...?

So can anyone explain the detailed mechanism? Or it's been done before?

 

[AndyW]

Hello! That sounds like a very interesting observation. It is possible that what you observed is a phenomenon known as the Leidenfrost effect. This occurs when a liquid, such as acetone, is in contact with a surface that is significantly hotter than its boiling point. The liquid then forms a vapor layer between itself and the surface, which reduces the contact and allows the liquid to "float" and move more freely. This effect is often seen when droplets of water are placed on a hot pan and appear to skate around rather than immediately evaporating.

In your case, the bubbles of acetone are likely experiencing the same effect, allowing them to move without the hindrance of friction. The bouncing off of obstacles is likely due to the vapor layer being disrupted and the bubble losing its "floatation."

As for the soliton theory, it is possible that the bubbles are behaving like solitons, which are self-reinforcing wave patterns that can travel without dispersing. However, further research would need to be done to confirm this.

It is also possible that the precise viscosity and evaporation rate of acetone are contributing factors to this phenomenon, but more research would need to be done to fully understand the mechanism at play.

Overall, your observation is certainly an interesting one and may have potential for further study. Thank you for sharing it with us!

 

[sir-pinski]

Thank you for sharing your observation with us! It sounds like you had quite an interesting experience in the lab. The phenomenon you observed with the acetone bubbles is known as the Leidenfrost effect. This occurs when a liquid is in contact with a surface that is significantly hotter than its boiling point, creating a layer of vapor between the liquid and the surface. This vapor layer reduces the contact between the liquid and the surface, resulting in the liquid "hovering" and exhibiting frictionless movement.

In the case of the acetone bubbles, the heat from the hot plate caused the liquid to evaporate quickly, creating a vapor layer that allowed the bubbles to move without any resistance. This is why the bubbles appeared to act like a ball on a frictionless surface, as there was no contact between the bubbles and the beaker walls.

As for why this phenomenon only occurs with acetone and not 2-propenal, it could be due to the different boiling points and viscosities of the two liquids. Acetone has a lower boiling point and lower viscosity compared to 2-propenal, which may make it more susceptible to the Leidenfrost effect.

Overall, your observation is a great example of the interesting and complex behavior of fluids. Thank you for sharing and sparking curiosity about this phenomenon!