To determine which factor plays the most important role in allowing the decomposition of magnesium oxide (MgO) into magnesium (Mg) and oxygen (O₂), let's analyze the given reaction:
[tex]\[
MgO (s) + 601.7 \text{ kJ} \rightarrow Mg (s) + \frac{1}{2} O_2 (g)
\][/tex]
Here, we see that 601.7 kJ of energy is required for the reaction to proceed. To understand which factor is most important, let's explore each given factor one by one:
1. Temperature: This reaction specifically mentions the need for 601.7 kJ of energy. Generally, supplying energy to a reaction can be achieved by increasing the temperature. Higher temperature provides the needed energy to overcome the activation energy barrier, enabling the decomposition reaction to occur.
2. Concentration: While concentration can influence the rate of reactions in solutions or gases, it is less relevant for this solid-state reaction. MgO decomposing into its elemental components is not a function of the concentration of reactants because it primarily involves a single solid reactant.
3. Pressure: Pressure mainly affects reactions involving gases. In this decomposition reaction, the solid MgO is converting into solid Mg and gaseous O₂, but pressure does not have as significant an impact on decomposing solids compared to temperature.
4. Surface Area: Surface area can affect the rate of reactions involving solids since greater surface area can increase the exposure to reactants or catalysts. However, this decomposition reaction is more energy-dependent rather than surface-dependent because of the high energy required.
Considering that the reaction needs a considerable amount of energy (601.7 kJ) to take place,
the temperature is the most critical factor because it supplies the necessary energy to drive the reaction forward.
Thus, the factor that plays the most important role in allowing this reaction to occur is:
[tex]\[
\boxed{\text{temperature}}
\][/tex]
