حرق المغنيسيوم في الجليد الجاف

يواصل المغنيسيوم الاحتراق في ثاني أكسيد الكربون الصلب، مختزلاً CO₂ إلى كربون

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

الهدف

إظهار قدرة المغنيسيوم على اختزال ثاني أكسيد الكربون، مما يتحدى المفهوم الخاطئ بأن CO₂ يطفئ الحرائق دائماً.

الخلفية

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.

تحذيرات السلامة

  • 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

معدات الوقاية الشخصية المطلوبة

goggles gloves lab_coat face_shield

المواد

  • 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

المعدات

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

الإجراء

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 دقيقة 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 دقيقة
3

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

2 دقيقة 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 دقيقة
5

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

3 دقيقة 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 دقيقة 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 دقيقة

النتائج المتوقعة

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.

التنظيف

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

التفاصيل

الفئة
Classroom Demonstrations
الصعوبة
Advanced (University)
المدة
25 دقيقة
التكلفة التقديرية
$15,00
الخطوات
7
المواد
3

مزيد من التجارب

التجميد الفوري: الماء المبرد فائقاً 120 min الكأس المختفي (توافق معامل الانكسار) 15 min الكيمياء الضوئية مع اللومينول 30 min تفاعل الثيرميت 30 min تفاعل الصوديوم مع الماء 25 min تفاعل بريغز-راوشر المتذبذب 40 min تفاعل ساعة اليود 45 min سائل غير نيوتوني: أوبليك 20 min عمود كثافة قوس قزح 30 min معجون أسنان الفيل 20 min

Frequently Asked Questions

What is the objective of حرق المغنيسيوم في الجليد الجاف?
إظهار قدرة المغنيسيوم على اختزال ثاني أكسيد الكربون، مما يتحدى المفهوم الخاطئ بأن CO₂ يطفئ الحرائق دائماً.
How difficult is حرق المغنيسيوم في الجليد الجاف?
This experiment is rated as Advanced (University). It takes approximately 25 minutes to complete.
What safety precautions are needed for حرق المغنيسيوم في الجليد الجاف?
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 حرق المغنيسيوم في الجليد الجاف?
The main materials required are: Magnesium ribbon, Dry ice block, Tongs (long-handled).
What results should I expect from حرق المغنيسيوم في الجليد الجاف?
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.