Magnésio Ardendo em Gelo Seco

O magnésio continua ardendo em dióxido de carbono sólido, reduzindo o CO₂ a carbono

Classroom Demonstrations Advanced (University) 25 min ~$15,00

Objetivo

Demonstrar que o magnésio pode reduzir o dióxido de carbono, desafiando o equívoco de que o CO₂ sempre apaga incêndios.

Contexto

Magnesium burns so intensely (over 3000°C) that it can reduce carbon dioxide to elemental carbon. When a burning magnesium ribbon is placed in a cavity carved into dry ice (solid CO₂), it continues to burn brilliantly white, producing magnesium oxide (white powder) and elemental carbon (black specks). This reaction (2Mg + CO₂ → 2MgO + C) dramatically shows that CO₂ is not always an effective fire extinguisher and that thermodynamic favorability depends on the specific reactants involved.

Avisos de segurança

  • Burning magnesium is extremely bright — never look directly at it without shade protection
  • Dry ice causes frostbite on contact — never handle with bare hands
  • Perform behind a safety shield
  • Keep a fire-resistant mat underneath
  • Do not attempt to extinguish burning Mg with water — explosion risk
  • Ensure ventilation — CO₂ accumulation in enclosed spaces is dangerous

EPI necessário

goggles gloves lab_coat face_shield

Materiais

  • Magnesium ribbon (30 cm)
    Clean, bright surface
  • Dry ice block (1 kg)
    Solid CO₂ (−78.5°C)
  • Tongs (long-handled) (1)
    For handling dry ice

Equipamentos

Safety shield Fire-resistant mat Chisel or screwdriver (for carving cavity in dry ice) Lighter or matches Welding goggles or #14 shade glass

Procedimento

1

Using tongs, carve a small cavity (about 3 cm deep) in the dry ice block. Place the dry ice on a fire-resistant mat.

3 min Wear insulated gloves for dry ice
2

Set up the safety shield between the demonstration and the audience. Distribute welding goggles or instruct everyone to look away when ignited.

2 min
3

Light one end of the magnesium ribbon. Once burning, quickly place it in the dry ice cavity using tongs.

2 min Do not look directly at the flame
4

Place another piece of dry ice on top to create a CO₂ atmosphere around the burning magnesium.

2 min
5

Observe: the magnesium continues to burn with an intense white flame inside the CO₂ environment. It does NOT go out.

3 min Maintain safe distance
6

After the reaction, examine the residue: white MgO powder and black carbon specks. Discuss the reaction: 2Mg + CO₂ → 2MgO + C.

8 min Wait for residue to cool completely
7

Discuss implications for fire safety: why Mg fires cannot be extinguished with CO₂, water, or standard fire extinguishers.

5 min

Resultados esperados

The magnesium continues to burn brilliantly inside the dry ice. After the reaction, white MgO and black carbon specks are visible in the dry ice cavity. This proves CO₂ has been reduced to elemental carbon.

Limpeza

Allow all residues to cool and dry ice to sublimate. Sweep up MgO and carbon residue. No chemical waste disposal needed.

Detalhes

Categoria
Classroom Demonstrations
Dificuldade
Advanced (University)
Duração
25 min
Custo estimado
$15,00
Passos
7
Materiais
3

Mais experimentos

Béquer Desaparecendo (Correspondência de Índice de Refração) 15 min Coluna Arco-Íris de Densidades 30 min Congelamento Instantâneo: Água Super-resfriada 120 min Fluido Não Newtoniano: Oobleck 20 min Pasta de Dente de Elefante 20 min Quimioluminescência com Luminol 30 min Reação da Termite 30 min Reação do Relógio de Iodo 45 min Reação do Sódio com Água 25 min Reação Oscilante de Briggs-Rauscher 40 min

Frequently Asked Questions

What is the objective of Magnésio Ardendo em Gelo Seco?
Demonstrar que o magnésio pode reduzir o dióxido de carbono, desafiando o equívoco de que o CO₂ sempre apaga incêndios.
How difficult is Magnésio Ardendo em Gelo Seco?
This experiment is rated as Advanced (University). It takes approximately 25 minutes to complete.
What safety precautions are needed for Magnésio Ardendo em Gelo Seco?
Key safety precautions include: Burning magnesium is extremely bright — never look directly at it without shade protection; Dry ice causes frostbite on contact — never handle with bare hands; Perform behind a safety shield.
What materials are needed for Magnésio Ardendo em Gelo Seco?
The main materials required are: Magnesium ribbon, Dry ice block, Tongs (long-handled).
What results should I expect from Magnésio Ardendo em Gelo Seco?
The magnesium continues to burn brilliantly inside the dry ice. After the reaction, white MgO and black carbon specks are visible in the dry ice cavity. This proves CO₂ has been reduced to elemental carbon.