不饱和度计算器
根据分子式计算有机化合物的不饱和度。
Lattice Energy (U)
-756 kJ/mol
Lattice Energy (U) vs Cation Charge (z⁺)
公式
Born-Landé Equation for Lattice Energy
Formula
U = −(A × N_A × e² × z⁺ × z⁻) / (4πε₀ × r₀) × (1 − 1/n)
Simplified with constants combined: U = −(A × 1389.4 × z⁺ × z⁻ / r₀) × (1 − 1/n)
Where r₀ is in angstroms (pm/100), and 1389.4 kJ·Å/mol combines N_A, e², and 4πε₀.
Where:
计算示例
NaCl: z⁺ = 1, z⁻ = 1, r₀ = 281 pm, A = 1.748, n = 8.
- 01U = -(A × 1389.4 × z⁺ × z⁻ / r₀) × (1 - 1/n)
- 02r₀ = 281 pm = 2.81 Å
- 03U = -(1.748 × 1389.4 × 1 × 1 / 2.81) × (1 - 1/8)
- 04U = -(864.2) × (0.875)
- 05U = -756 kJ/mol
常见问题
What is lattice energy?
Lattice energy is the energy released when gaseous ions combine to form one mole of an ionic solid. Higher lattice energy means a more stable crystal.
What is the Madelung constant?
The Madelung constant accounts for the geometry of the crystal. For NaCl structure it is 1.748, for CsCl it is 1.763, for ZnS (zinc blende) it is 1.638.
What factors increase lattice energy?
Higher ion charges and shorter interionic distances increase lattice energy. MgO (2+, 2-) has much higher lattice energy than NaCl (1+, 1-).
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