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To determine whether Sulfide ion (S) is polar or nonpolar, the decisive question is whether the bond dipoles of the molecule cancel once its three-dimensional shape is taken into account. Sulfide ion is an elemental substance of sulfur. As set out in the S Lewis Structure Guide, S has 1 heavy atom.
The bond polarities follow from electronegativity. As a result, the species is a single atom carrying a net charge, so it is described by its charge and its hydration, not by a dipole moment.
For formulation and process work, the useful consequences are these: the calculated topological polar surface area is 0.0 Ų, 0 hydrogen-bond donors and 0 hydrogen-bond acceptors, the Crippen calculated partition coefficient is logP ≈ 0 and the calculated molar refractivity is 7.37 cm³ mol⁻¹. A calculated logP of about zero means the descriptor finds no preference for octanol over water; for a molecule this small the partitioning is then decided by specific interactions rather than by bulk polarity. PubChem’s curated experimental record adds: Sulfide ion is Solid.
Sulfide ion (CAS 18433-24-4) is an elemental substance of sulfur, supplied as an industrial chemical. Its polarity matters for the same reason it matters for any substance of this class: it decides which phases the material will enter, how strongly it adsorbs onto polar surfaces, and how much energy a separation will cost.
The measured physical behaviour recorded for this substance is consistent with that picture. Physical Description: Solid. Melting Point: 112 °C. These are database values and should be read with the conditions (temperature, purity, pressure) that the source states.
No dilute-gas permittivity is reported here: the Debye estimate would have to inherit a dipole moment that this method does not deliver reliably for this class of compound (the species is ionic or carries a net charge, so the dipole depends on the choice of origin and is not a molecular constant), and for an ionic substance the equation does not apply at all.
The structure carries no strongly polar functional group, so the intermolecular forces are dominated by dispersion rather than by dipole–dipole attraction or hydrogen bonding.
No GHS hazard statements were retrieved for this substance from the public record used here, so no classification is asserted. The applicable classification must be taken from the supplier’s safety data sheet and from the ECHA or OSHA/NIOSH tables for CAS 18433-24-4.
In short, specify Sulfide ion by assay, water content, impurity profile, packaging and transport class, and state the intended application on the enquiry. The polarity analysis above explains behaviour in use; it does not replace a specification.
The comparison below places S next to structurally related substances from the same catalogue. Dipole moments come from one consistent protocol (GFN2-xTB//MMFF94, gas phase, single conformer) and are quoted only where that protocol has been validated; where it has not, the cell says so instead of giving a number. Permittivities are dilute-gas estimates from the Debye equation, logP values are Crippen calculations, and the solubility column is a qualitative inference from the calculated descriptors rather than a measurement.
| Compound | Dipole Moment | Approx. Gas εr | log P / XlogP | Water Solubility Behavior | Industrial Sourcing |
|---|---|---|---|---|---|
| S | not applicable (ion) | — | logP ≈ 0 | Solid | See supply listing |
| H2S | ≈0.97 D (lit.) | ≈1.0107 | logP ≈ 0.11 | Moderate (inferred from logP) | See supply listing |
| HS | non-zero, not quoted | — | logP ≈ 0.38 | Moderate (inferred from logP) | See supply listing |
| BaS | non-zero, not quoted | — | — | Dissolves by dissociation; ionic hydration dominates | See supply listing |
| CaS | non-zero, not quoted | — | — | Dissolves by dissociation; ionic hydration dominates | See supply listing |
The spread across this table is the point: composition alone does not set the polarity verdict. S sits where it does because of the balance between weak dispersion forces and the asymmetry of its shape, and any of the neighbouring entries can be the better choice once the temperature, the phase and the required polarity window are fixed.
“S is polar, but no magnitude is quoted: the species is ionic or carries a net charge, so the dipole depends on the choice of origin and is not a molecular constant. A calculated logP of about zero tells you it partitions roughly equally between octanol and water. The curated experimental record is consistent: Solid.”
Regulatory status is specific to the substance and to the jurisdiction, and it changes. For CAS 18433-24-4 the authoritative public sources are the ECHA registered-substance database for the EU, and the OSHA and NIOSH tables for occupational exposure in the United States.
No GHS hazard statements for this substance were retrieved from the public database used to build this article, so none are asserted here. Treat the absence of a quoted classification as an instruction to check the supplier’s safety data sheet, not as evidence that the substance is harmless.
No occupational exposure limit for this substance is quoted in this article, because none was present in the database record used here. Publishing a limit that is not on the record would be worse than publishing none: obtain the applicable value from the OSHA Z-table, the NIOSH pocket guide or the equivalent national instrument before designing the ventilation or monitoring programme.
From a compliance and sustainability standpoint, the polarity of S is a means rather than an end. It determines which solvent can replace another, how completely the substance can be recovered from a stream, and how much energy the separation will cost — so it belongs in the process justification, while the hazard classification and the exposure limits belong in the safety case.
A purchase enquiry for Sulfide ion (CAS 18433-24-4) should state the grade, assay basis, permitted impurity limits, water content, packaging, and the transport and regulatory status required for the destination market. Where the substance is used as a reagent or intermediate, the impurity profile usually matters more than the nominal percentage.
Because polarity governs phase behaviour, it also governs recovery: a polar molecule is easier to strip from a non-polar stream and harder to dry than a non-polar one, and vice versa. Confirm the Guidechem supply listing for current availability and compare lots on the certificate of analysis rather than on the label alone.
Looking for commercial bulk supplies or technical documentation for Sulfide ion (CAS 18433-24-4)?
No single calculated number was obtained for Sulfide ion with the method used here. The polarity is argued from the structure, the bond electronegativity differences and the molecular symmetry instead.
The species is ionic or carries a net charge, so the dipole depends on the choice of origin and is not a molecular constant. Rather than publish a number that would be misleading, the article argues the polarity from structure and symmetry; the literature value can be looked up in the NIST or CRC tables if a number is required.
Whether the individual bond dipoles cancel depends on how the bonds are arranged in three dimensions. Two identical bonds pointing in opposite directions cancel; the same two bonds at an angle do not.
No permittivity is quoted: the Debye dilute-gas equation does not apply to a charged species.
Not in routine tabulations. Snyder P′ was developed for conventional liquid chromatographic solvents, and this substance is outside the scope of that scale. Dipole moment, calculated logP and hydrogen-bond counts are the descriptors used here instead.
The curated database record states: Solid. The calculated logP of about zero is consistent with that behaviour.
Grade, assay basis, water content, the declared impurity profile, packaging and the transport classification, plus the regulatory status required for the destination market. Confirm the hazard classification from the supplier’s safety data sheet, since none is asserted here.
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