To determine which factor plays the most crucial role in allowing the decomposition of magnesium oxide (MgO) into magnesium (Mg) and oxygen (O₂) to occur, we need to analyze the given reaction:
[tex]\[ MgO (s) + 601.7 \, \text{kJ} \rightarrow Mg (s) + \frac{1}{2} \, O_2 (g) \][/tex]
From the reaction, we can see that:
1. Energy Requirement: The reaction requires a significant amount of energy, specifically 601.7 kJ to decompose one mole of MgO. This indicates that the reaction is highly endothermic, meaning it absorbs heat from its surroundings.
Given the factors to consider:
- Temperature: As the reaction is endothermic, increasing the temperature would provide the necessary energy to overcome the activation energy barrier, making it possible for the reaction to proceed. In other words, higher temperatures supply the energy needed to drive the reaction forward.
- Concentration: Concentration typically affects reaction rates for reactions involving solutions or gaseous reactants. However, in this case, we are dealing with solid MgO and solid Mg, where the decomposition doesn't directly depend on the concentrations of solutions or gases.
- Pressure: Pressure mainly influences reactions involving gases, particularly those where the volume of gas changes significantly. In this reaction, pressure is less relevant since the primary concern is the energy needed to break the bonds in the solid MgO.
- Surface Area: Increasing surface area generally enhances the rate of reaction, especially for solid reactants. However, it still doesn't provide the necessary energy for the decomposition.
Therefore, among the given factors, the most critical one is:
Temperature:
Temperature plays the most important role in allowing this reaction to occur because it supplies the required energy (601.7 kJ) to decompose magnesium oxide into magnesium and oxygen.
