Seeing Inside A Thermite Reaction

Key Concepts

• Thermite Reaction: A highly exothermic chemical reaction between a metal oxide and a metal, typically iron oxide and aluminum.
• Crucible Modification: Cutting a crucible in half and attaching thermally resistant glass windows for observation.
• High-Temperature Observation: The challenges and visual phenomena associated with observing extreme temperature reactions.
• Pulsing Reaction Phenomenon: An observed rhythmic expansion and contraction during the thermite reaction.
• Gas Escape Hypothesis: A proposed explanation for the pulsing phenomenon involving gas release.

Thermite Reaction Observation with Modified Crucible

The experiment involves observing a thermite reaction, specifically using iron oxide and aluminum metal, within a modified crucible. The crucible has been cut in half, and two pieces of 4 mm thick, thermally resistant glass have been attached to serve as windows into the reaction. This modification was undertaken despite skepticism that it would be impossible to see anything or that the glass would break. The intention is to analyze and understand the visual phenomena occurring during the reaction.

Challenges and Material Properties

The specially treated glass is intended to resist shattering upon contact with molten metal. However, the melting temperature of silica, the primary component of glass, is approximately 1,700° C, which is lower than the temperature of the thermite reaction. This highlights a significant technical challenge in maintaining the integrity of the observation windows.

The Thermite Reaction and Visual Phenomena

The thermite reaction is initiated by an igniter and propagates outwards in all directions. Visually, the spread of the reaction is described as resembling ants, mold, or something organic in its expansion. A notable observation is a "pulsing" effect, characterized by rhythmic expansions. This pulsing is likened to a living organism, with one observer stating, "It's living. Yeah. That's what it looks like." This pulsing behavior was an unexpected discovery, even after performing the reaction for an extended period.

Hypothesis for Pulsing Phenomenon

A hypothesis is proposed to explain the observed pulsing. It is suggested that gas is escaping upwards, and this release of gas is what causes the pulsing. The theory posits that as gas heats up, it shoots upwards, creating space for the next wave of reaction to occur. This cyclical process of heating, gas release, and expansion is what creates the visual pulsing effect.

Reaction Temperature and GoPro Incident

The extreme heat of the reaction is emphasized, with the statement, "Wow. That is hot. That is really hot." Unfortunately, the observation setup, which included a GoPro camera, was compromised during the experiment. The transcript notes, "Oh no, the GoPro. Oh boy. Oh no. Oh no. That's the end of the GoPro." This indicates that the camera was destroyed by the heat or the reaction itself, despite the efforts to create an observational setup. The situation is humorously acknowledged with the remark, "I mean, this is impressive work for a camera that's on fire."

Synthesis and Conclusion

This experiment aimed to provide a clear, on-camera view of a thermite reaction through a novel modification of the reaction vessel. While the visual spectacle of the reaction, particularly the unexpected pulsing phenomenon, was captured, the extreme temperatures proved challenging, leading to the destruction of the recording equipment. The pulsing is hypothesized to be a result of gas escaping, creating a rhythmic expansion. The experiment underscores the intense nature of thermite reactions and the difficulties in observing such events safely and effectively.