How does the Mg ribbon differ from the Magnesium Oxide formed after burning the metal?

Answer 1

2Mg^2+ + O2 -- > 2MgO

This is the chemical reaction occurring when burning magnesium. When burning the metal in air, which is slightly less than 20% O2, there is less O2 for the Mg to react with than there would be in a pure O2 environment.

In the high O2 concentration environment the Mg doesn't have to "wait" for more O2 to diffuse into the area before the reaction can occur. In the case of burning Mg in air, the O2 conc. is much lower, and therefore depleted faster, and in turn must "wait" for more O2 to diffuse into the area.

The reason it seems to burn hotter and bright is because all the energy being release from the combustion is able to happen much faster in the pure O2 environment.

Provided you were burning the same mass of Mg, the same TOTAL amount of energy is released in both reactions, the pure O2 environment just allows it to happen in a shorter time frame.

Energy released reacting (enthlapy of combustion)1 mol of Mg = -1200 kJ/mol regardless of the O2 saturation in the environment. Reacting it in a pure oxygen environment just allows the reaction to happen faster.

Answer 2

The actual reaction is the production of magnesium oxide in the presence of oxygen. The atmospheric oxygen percentage is approximately 21% only.

The reaction between magnesium and nitrogen is much slower than the reaction between that and oxygen.

Answer 3

Burning magnesium ribbon in oxygen produces a brighter and stronger white flame than in air. Air has only 27% oxygen, so is weaker that pure oxygen gas.

Answer 4

when magnesium ribbon burns in air, carbon dioxide also reacts with the magnesium. In oxygen, carbon dioxide is not present, so only oxygen reacts with the metal.

Answer 5

Mg (metallic element) in ribbon and MgO (oxide compound of oxygen and magnesium, white powder)