Dielectric Constant
The dielectric constant (ε, Greek epsilon) is a property of a solvent. It is a measure of how well the solvent reduces interactions between ions in solution.
A dielectric constant greater than or equal to 20 means the medium is a good solvent (ie, at 20°C dH2O has an ε ≈ 80) and an ε below that means the medium is a poor solvent (ie,at 20°C acetic acid has an ε ≈ 6).
F = [ k · q1 · q2 ] / [ ε · r2 ]
| F | Given two charges (ie, Na+ and Cl-, they exert a force F on each other, either attractive or repulsive. |
|---|---|
| k | Proportionality constant. |
| q1 q2 | Magnitude of the charges. |
| r | Distance between the charges. |
| ε | Dielectric constant of the surrounding medium. |