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Does an ice cube have heat energy (kinetic energy)? If so, does a glass of water with ice have more heat energy than a glass of water without ice?

water and ice

The ice cube does have heat, and even if the ice is still, its molecules are in motion (have kinetic energy). You can know something has heat if it can warm up something else: For instance liquid nitrogen has a very low boiling point (-200C). If you were to put ice cubes from the freezer into a cup of it, it would immediately begin boiling vigorously.

However, pound for pound, ice has less heat than water. Therefore, if you were to take two identical glasses of water, remove some of the water from one, freeze it, and replace it in the glass, there would be less heat in it than in the other glass. However, if you took two identical glasses of water and added ice to one, there would actually be more heat, simply because there is more material.

Finally, even in the second case, the water with ice will be colder (i.e. at a lower temperature). In both cases the water continues to give its heat to the ice until everything is at the same temperature. So until the ice is totally melted, the water with ice will have lost some heat compared to the water without ice. In short everything has at least a little bit of heat, though cold things absorb heat from warm things.

Answered by:

Leon Webster
PhD Candidate
University of Michigan

Submitted by:

Matt Lafond, 6th Grade Science Teacher from Wayland Middle School in Wayland, MA