Answer: increases by
As a chlorine atom becomes a negative ion, the atom "increases by" an electron
Explanation:
Chlorine atom has an atomic number of 17, and an electronic configuration of 1s2, 2s2 2p6, 3s2 3p5 showing 7 valence electrons in its outermost shell.
Hence, it receives a single electron to achieve a stable octet structure with electronic configuration of
1s2, 2s2 2p6, 3s2 3p6. Therefore, Cl- is a univalent negative ion with 8 valence electrons in its outermost shell. The increase is shown below
Cl + e- --> Cl-
Thus, as a chlorine atom becomes a negative ion, the atom "increases by" an electron
Answer:
- 416 kJ/mol
Explanation:
The standard enthalpy of the reaction (Δ
H
∘
rxn) is independent of the pathway, so it can be calculated by the enthalpy of formation of the reactants and the products:
Δ
H
∘
rxn = ∑n*Δ
H
∘f products - ∑n*Δ
H
∘f reactants
Where n is the number of moles in the balanced reaction. So, for the reaction given:
Na₂O(s) + 1/2O₂(g) → Na₂O₂(s)
Because O₂ is formed by only one elements, its Δ
H
∘f is 0 kJ/mol:
-89.0 = (1*(-505) - (1*Δ
H
∘fNa₂O)
Δ
H
∘fNa₂O = -505 + 89
Δ
H
∘fNa₂O = - 416 kJ/mol
Because carbon has two double bonds which is equal to 8 electrons so therefore the octet rule is fulfilled.
