The Lewis structure the student drew is incorrect. The total number of electrons in bonds and lone pairs is equal to the total number of valence electrons available, then a valid Lewis structure is produced.
The correct structure is the following:
The structure that was drawn by the student was incorrect because the total number of electrons around Oxygen were incorrect, there were 6 instead of 8, which was against the octet rule. The correct structure should have 8 electrons around each atom.
Answer:
Explanation:
The solution contain 0.01 M concentration of Ba²⁺
0.01M concentration of Ca²⁺
Ksp ( solubility constant) for BaSO₄ = 1.07 × 10⁻¹⁰
Ksp for CaSO₄ = 7.10 × 10⁻⁵
(BaSO₄) = (Ba²⁺) (SO₄²⁻)
1.07 × 10⁻¹⁰ = 0.01 M (SO₄²⁻)
1.07 × 10⁻¹⁰ / 0.01 = ( SO₄²⁻)
1.07 × 10⁻⁸ M = ( SO₄²⁻)
so the minimum of concentration of concentration sulfate needed is 1.07 × 10⁻⁸ M
For CaSO₄
CaSO₄ = ( Ca²⁺) ( SO₄²⁻)
7.10 × 10⁻⁵ = 0.01 (SO₄²⁻)
(SO₄²⁻) = 7.10 × 10⁻⁵ / 0.01 = 7.10 × 10⁻³ M
so BaSO₄ will precipitate first since its cation (0.01 M Ba²⁺) required a less concentration of SO₄²⁻ (1.07 × 10⁻⁸ M ) compared to CaSO₄
b) The minimum concentration of SO₄²⁻ that will trigger the precipitation of the cation ( 0.01 M Ba²⁺) that precipitates first is 1.07 × 10⁻⁸ M