? Sig) + e 75 (g) S (g) + e 7 52 (g) Stg) 75″(5) + 5 (g) 7 Sig) + e 75 (g) + e’
The Correct Answer and Explanation is:
The correct reaction that represents the second electron affinity of sulfur (S) is:
S⁻(g) + e⁻ → S²⁻(g)
Explanation:
The electron affinity refers to the energy change that occurs when an electron is added to a neutral atom or ion in the gas phase. The first electron affinity is the energy released when a neutral atom gains an electron, forming a negatively charged ion. However, when a second electron is added to a negatively charged ion, the process becomes more complex, as there is a repulsion between the negatively charged ion and the incoming electron.
The second electron affinity, specifically for sulfur, involves adding an additional electron to the already negatively charged S⁻ ion, resulting in the formation of S²⁻. The key thing to note here is that adding an electron to a negatively charged species (S⁻) is energetically unfavorable, since there is an electron-electron repulsion. This means that the second electron affinity is typically positive, which implies that energy must be supplied to overcome this repulsion.
In the case of sulfur, the second electron affinity is less negative than the first electron affinity. The first electron affinity for sulfur is the energy released when a neutral sulfur atom (S) gains an electron to become S⁻. On the other hand, the second electron affinity for sulfur is the energy change when an electron is added to the already negatively charged S⁻ ion to form S²⁻.
This reaction is a good example of the trend seen in many elements. The addition of the second electron is less favorable because of the increasing repulsion between the negative charge on the ion and the incoming electron. For sulfur, this repulsion results in a positive value for the second electron affinity, which makes this process endothermic.
Thus, the second electron affinity of sulfur is best represented by the equation:
S⁻(g) + e⁻ → S²⁻(g).
