Question
Q1. For each pair, choose the compound with larger lattice energy and explain your choice.
a). CaO or CaS
b). BaO or SrO
a). CaO or CaS
b). BaO or SrO
Answers
GPT-4o mini
Lattice energy is the measure of the strength of the forces between the ions in an ionic solid. It is largely determined by the charges of the ions and the distance between them (typically represented by ionic radii). According to Coulomb's Law, lattice energy increases with higher charges and decreases with larger ionic radii.
### a) CaO or CaS
**Lattice Energy Comparison**: **CaO has larger lattice energy than CaS.**
**Explanation**:
- CaO consists of Ca²⁺ and O²⁻ ions, while CaS consists of Ca²⁺ and S²⁻ ions.
- Both compounds have ions with the same charges (2+ and 2-).
- However, the oxide ion (O²⁻) is smaller than the sulfide ion (S²⁻). The smaller ionic radius of O²⁻ means that the distance between the Ca²⁺ and O²⁻ ions is shorter than that between the Ca²⁺ and S²⁻ ions in CaS.
- Thus, the attractive forces between Ca²⁺ and O²⁻ in CaO are stronger than those between Ca²⁺ and S²⁻ in CaS, resulting in CaO having larger lattice energy.
### b) BaO or SrO
**Lattice Energy Comparison**: **SrO has larger lattice energy than BaO.**
**Explanation**:
- Both SrO and BaO consist of +2 ions (Sr²⁺ and Ba²⁺) and O²⁻ ions.
- However, Sr²⁺ has a smaller ionic radius compared to Ba²⁺. As a result, the distance between the Sr²⁺ and O²⁻ ions is less than that between Ba²⁺ and O²⁻ ions in BaO.
- Although both compounds contain the same charges, the shorter distance and smaller radius of Sr²⁺ contribute to a stronger attraction between the ions in SrO relative to BaO.
- Therefore, SrO has a larger lattice energy than BaO due to the stronger ionic interactions.
In summary:
a) **CaO** has larger lattice energy than CaS.
b) **SrO** has larger lattice energy than BaO.
### a) CaO or CaS
**Lattice Energy Comparison**: **CaO has larger lattice energy than CaS.**
**Explanation**:
- CaO consists of Ca²⁺ and O²⁻ ions, while CaS consists of Ca²⁺ and S²⁻ ions.
- Both compounds have ions with the same charges (2+ and 2-).
- However, the oxide ion (O²⁻) is smaller than the sulfide ion (S²⁻). The smaller ionic radius of O²⁻ means that the distance between the Ca²⁺ and O²⁻ ions is shorter than that between the Ca²⁺ and S²⁻ ions in CaS.
- Thus, the attractive forces between Ca²⁺ and O²⁻ in CaO are stronger than those between Ca²⁺ and S²⁻ in CaS, resulting in CaO having larger lattice energy.
### b) BaO or SrO
**Lattice Energy Comparison**: **SrO has larger lattice energy than BaO.**
**Explanation**:
- Both SrO and BaO consist of +2 ions (Sr²⁺ and Ba²⁺) and O²⁻ ions.
- However, Sr²⁺ has a smaller ionic radius compared to Ba²⁺. As a result, the distance between the Sr²⁺ and O²⁻ ions is less than that between Ba²⁺ and O²⁻ ions in BaO.
- Although both compounds contain the same charges, the shorter distance and smaller radius of Sr²⁺ contribute to a stronger attraction between the ions in SrO relative to BaO.
- Therefore, SrO has a larger lattice energy than BaO due to the stronger ionic interactions.
In summary:
a) **CaO** has larger lattice energy than CaS.
b) **SrO** has larger lattice energy than BaO.