Write a balanced equation for the reaction of the magnesium and the oxygen (02), including their physical states.
The correct answer and explanation is :
Balanced Chemical Equation:
2Mg (s)+O2(g)→2MgO (s)2\text{Mg (s)} + \text{O}_2\text{(g)} \rightarrow 2\text{MgO (s)}
Explanation (300 words):
The reaction between magnesium (Mg) and oxygen (O₂) is a synthesis (combination) reaction, where two elements combine to form a compound. When magnesium metal burns in the presence of oxygen, it forms magnesium oxide (MgO) — a white, powdery solid.
In this reaction, magnesium acts as a reducing agent, and oxygen acts as an oxidizing agent. Here’s what happens on the atomic level:
- Magnesium atoms each lose two electrons to form Mg²⁺ ions. This is an oxidation process.
- Oxygen molecules (O₂) gain four electrons (two per oxygen atom) to form two O²⁻ ions. This is a reduction process.
These oppositely charged ions then attract each other, forming an ionic compound: magnesium oxide (MgO). The formula for magnesium oxide is MgO because magnesium forms a 2+ ion and oxygen forms a 2− ion, so the charges balance in a 1:1 ratio.
To write and balance the equation:
- One molecule of oxygen (O₂) contains two atoms of oxygen.
- Each magnesium oxide (MgO) unit needs one oxygen atom.
- So, two Mg atoms are needed to react with one O₂ molecule, forming two MgO units.
Thus, the balanced equation is: 2Mg (s)+O2(g)→2MgO (s)2\text{Mg (s)} + \text{O}_2\text{(g)} \rightarrow 2\text{MgO (s)}
Physical States:
- Mg (s): solid metal
- O₂ (g): gaseous oxygen
- MgO (s): solid magnesium oxide
This reaction is exothermic, meaning it releases energy in the form of heat and light. That’s why magnesium burns with a bright white flame when heated in air or pure oxygen. This property is used in fireworks and flares.