thermochemistry

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

Dean Campbell | Tue, 06/04/2024 - 11:00

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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.

A Logical Way to Teach Hess’s Law of Heat Summation

Michael Jansen | Thu, 04/25/2024 - 11:50

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From bond energies to thermochemical equations, explore the convergence of pathways to the same result in teaching Hess’s Law of Heat Summation.

The Chemistry of Pharaoh's Serpent with Calcium Gluconate

Tom Kuntzleman | Wed, 02/28/2024 - 13:59

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Pharaoh's serpent is the name of a very interesting chemical reaction that produces a snake-like foam. Unfortunately, it requires the use of a toxic mercury compound. Explore this very similar reaction that can be achieved quite simply by using fuel tablets and calcium gluconate tablets and learn a lot about the chemistry that is involved!

A Quick and Accurate Determination of the Heat of Fusion of Water

Michael Jansen | Wed, 01/24/2024 - 10:21

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This activity allows for the simple and accurate determination of the heat of fusion, ΔH_fusion, of water at 0°C.

Burning paper towels soaked in various metal nitrates

Tom Kuntzleman | Mon, 10/16/2023 - 13:04

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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!

Using Thermochemistry to Verify a Claim

Michael Jansen | Wed, 09/06/2023 - 07:20

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In this activity, students use their knowledge of thermochemistry to investigate a claim related to a kerosene fueled campstove.

Chemical Activities Involving Reversible Thermochromic Pigments

Dean Campbell | Wed, 08/16/2023 - 07:17

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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.