Melting and Viscosity

Most recent answer: 02/10/2010

Q:
Does an ice cube melt quicker in a liquid with low viscosity than in a liquid with high viscosity? Why? Likewise, does the color of a liquid affect the rate at which an ice cube melts when submerged in that liquid?
- jean (age 12)
Sheridan, Wyoming USA
A:
It's hard to change the viscosity of a water solution without changing other properties which affect the melting rate. These properties include the total amount of solute, which affects the melting temperature, and the density, which affects whether the melted water sinks, floats, or mixes easily. One way to do this would be to make similar solutions of water/glycerol and water/ethanol with similar melting points. The glycerol solution will have much higher viscosity.

My guess is that under most conditions the low-viscosity solution will melt the ice faster. That's because it allows faster convective stirring. You could try the experiment. To be more confident that the viscosity was the key factor, you need to try a variety of solutions with different alcohols, salts, and maybe polymers (like gelatin) to vary different factors and viscosity independently.

Mike W.

(published on 02/10/2010)