Ice and Boiling Water Experiment: Discover the Surprising Results

[BL4CKCR4Y0NS]

"Ice In Boiling Water?"

If you nearly fill a test tube with cool water and then take a piece of ice and press it down on the bottom of the tube with a small weight, heat the test time with a flame that licks only the upper part of the tube, the water will start to boil sooner or later.But the ice at the bottom will not melt.

What's going on?

 

[SpectraCat]

If you nearly fill a test tube with cool water and then take a piece of ice and press it down on the bottom of the tube with a small weight, heat the test time with a flame that licks only the upper part of the tube, the water will start to boil sooner or later.But the ice at the bottom will not melt.

What's going on?

Well, first of all I don't think your last statement is strictly correct, I mean, the ice will melt eventually if you just leave it sitting out at room temperature .. you don't need the flame. However, assuming that you have a long enough tube to observe the effect you mention, all that is going on is that it takes time for the different regions to reach thermal equilibrium with each other. Thermal transport in gases and liquids takes place largely through the phenomenon of convection, where less-dense, warmer "packets" of material rise up while more-dense, cooler packets fall down, leading to mixing. In a narrow test tube, it could easily take more time for this to occur than for the water near the top of the tube to reach the boiling point.

 

[BL4CKCR4Y0NS]

Yeah I took it straight out of a book and didn't understand...

So basically it just takes more time for it to melt because heat rises and the ice is at the bottom. Yeah?

 

[SpectraCat]

Yeah I took it straight out of a book and didn't understand...

So basically it just takes more time for it to melt because heat rises and the ice is at the bottom. Yeah?

Yes ... the situation would be different if you locally heated the bottom of the tube and had the ice at the top .. in that case, the convective mixing would be faster, since the heat transfer is going in the "favored" direction for convection .. sorry if that wasn't clear from the last post.

 

[PJC01]

This experiment demonstrates the concept of superheating, where water can reach a temperature above its boiling point without actually boiling. The ice at the bottom of the test tube acts as a nucleation point, providing a surface for bubbles to form and allowing the water to finally boil. This is because the boiling point of water is affected by pressure, and the weight of the ice creates a higher pressure at the bottom of the tube. As the water heats up, the pressure at the bottom of the tube increases, causing the boiling point to also increase. This allows the water to reach a higher temperature before boiling. Superheating can be a surprising and potentially dangerous phenomenon, as the water can suddenly boil and potentially cause burns or explosions. It is important to always use caution when heating liquids and to never heat water in a completely sealed container.