To determine which factor plays the most important role in allowing the decomposition of magnesium oxide ([tex]\( MgO \)[/tex]) into magnesium ([tex]\( Mg \)[/tex]) and oxygen ([tex]\( O_2 \)[/tex]), we need to analyze the specific conditions under which this reaction is facilitated, particularly focusing on the reaction's requirements and characteristics.
The reaction is as follows:
[tex]\[
MgO ( s )+601.7 \, \text{kJ} \rightarrow Mg ( s )+ \frac{1}{2} O_2(g)
\][/tex]
### Step-by-Step Solution:
1. Understanding the Reaction:
- This reaction is endothermic, meaning it requires the absorption of energy (601.7 kJ) to proceed. Endothermic reactions typically need an external source of energy to overcome the activation energy barrier.
2. Evaluating the Factors:
- Temperature:
- Raising the temperature provides the necessary thermal energy to overcome activation energy barriers, making it crucial for endothermic reactions.
- Concentration:
- Concentration generally affects the rate of reaction in solutions but is less significant for solid decomposition reactions.
- Pressure:
- Changes in pressure primarily affect reactions involving gases. In this case, the reaction involves solid magnesium oxide, solid magnesium, and a small amount of gaseous oxygen.
- Surface Area:
- Increased surface area can enhance reaction rates by exposing more reactant particles to each other. However, the decomposition of a solid into solid and gas is mostly driven by the input of energy.
3. Conclusion:
- Since the decomposition of [tex]\( MgO \)[/tex] is endothermic and requires a substantial amount of energy (601.7 kJ), the most crucial factor facilitating this reaction is temperature. By increasing the temperature, we supply the necessary energy to drive the reaction forward.
Therefore, the most important factor for the decomposition of magnesium oxide is:
Temperature
So, the answer to the question is indeed temperature.
