Amount and rate of heat transfer using iron spheres and liquid nitrogen

When iron spheres at room temperature are added to liquid nitrogen, the nitrogen boils as heat is transferred in from the iron. The amount of liquid nitrogen boiled depends on the amount of heat transferred, which depends on the mass of the iron added. However, the rate at which liquid nitrogen boils depends on the surface area of the iron in contact with the liquid nitrogen. These phenomena can be studied with experiments which measure the mass lost by the boiling liquid nitrogen.

Burning paper towels soaked in various metal nitrates

Igniting paper towels that have been soaked in concentrated potassium nitrate and allowed to dry yields a flame reminiscent of that produced by guncotton. Repeating this experiment with other metal nitrates produces flames with different colors, plus a few other chemical surprises! This series of experiments is fascinating and connects to a wide variety of chemical topics including combustion, redox reactions, chemical thermodynamics, and flame tests. You don't want to miss this one!

Chemical Activities Involving Reversible Thermochromic Pigments

The color of a thermochromic system depends on its temperature. The colors of leuco dye-based systems can also be influenced by adding acids or bases to the thermochromic reactions. These can be used to create colorful demonstrations of acid-base chemistry. Thermochromism found in color changing cups can also be used to visualize heat flow, and therefore thermodynamic principles, associated with stretching and contracting elastomers.

Seashell Chemistry

Placing dry ice in limewater is a great demonstration to accompany discussions on a variety of chemical topics, including the impact of ocean acidification on marine organisms that depend upon the formation of CaCO3.