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To determine whether calcium hydroxide (Ca(OH)2) 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. calcium hydroxide is an inorganic compound. As set out in the Ca(OH)2 Lewis Structure Guide, Ca(OH)2 has 1 heavy atom. For calcium hydroxide (USEPA/OPP Pesticide Code: 075601) ACTIVE products with label matches..
The bond polarities follow from electronegativity. Because the substance separates into ions, the molecule is polar but the magnitude of its dipole is not quoted here, because the species is ionic or carries a net charge, so the dipole depends on the choice of origin and is not a molecular constant.
For formulation and process work, the useful consequences are these: the calculated topological polar surface area is 30.0 Ų, 0 hydrogen-bond donors and 1 hydrogen-bond acceptor and the Crippen partition coefficient is not quoted, because the parameter set does not cover every element in the molecule. PubChem’s curated experimental record adds: calcium hydroxide is 0.2 % at 32 °F (NIOSH, 2024).
PubChem’s use and manufacturing record describes calcium hydroxide as follows: For calcium hydroxide (USEPA/OPP Pesticide Code: 075601) ACTIVE products with label matches. These applications are what make the polarity question practical — solvent choice, extraction recovery, cleaning and formulation all turn on how strongly the molecule interacts with polar phases.
The measured physical behaviour recorded for this substance is consistent with that picture. Solubility: 0.2 % at 32 °F (NIOSH, 2024). Physical Description: Calcium hydroxide is an odorless white granules.. Density: 2.24 at 68 °F (USCG, 1999) - Denser than water;. Melting Point: 1076 °F (Decomposes) (Loses H2O) (NIOSH, 2024). 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.
PubChem’s GHS record for this substance lists H314 (22.4%): Causes severe skin burns and eye damage [Danger Skin corrosion/irritation] and H315 (45.3%): Causes skin irritation [Warning Skin corrosion/irritation]. Those classifications, not the polarity of the molecule, normally determine packaging, labelling, ventilation and transport requirements.
In short, specify calcium hydroxide 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 Ca(OH)2 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 |
|---|---|---|---|---|---|
| CaH2O2 | non-zero, not quoted | — | — | 0.2 % at 32 °F (NIOSH, 2024) | See supply listing |
| HO | non-zero, not quoted | — | logP ≈ -0.18 | Moderate to high (inferred from logP < 0) | See supply listing |
| HCs2O | non-zero, not quoted | — | — | Dissolves by dissociation; ionic hydration dominates | See supply listing |
| SnO2 | non-zero, not quoted | — | — | Dissolves by dissociation; ionic hydration dominates | See supply listing |
| HORb2 | 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. Ca(OH)2 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.
“Ca(OH) 2 is an ionic substance, so the useful question is not "polar or nonpolar" but how the charge is distributed and how strongly the ions are hydrated. No calculated partition coefficient is quoted, because the Crippen parameter set does not cover every element in the molecule. The curated experimental record is consistent: 0.2 % at 32 °F (NIOSH, 2024).”
Regulatory status is specific to the substance and to the jurisdiction, and it changes. For CAS 1305-62-0 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.
PubChem’s GHS record for this substance lists H314 (22.4%): Causes severe skin burns and eye damage [Danger Skin corrosion/irritation] and H315 (45.3%): Causes skin irritation [Warning Skin corrosion/irritation]. These statements are the ones that must appear on the label and in section 2 of the safety data sheet; they, rather than the polarity of the molecule, drive classification, packaging group and transport documentation.
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 Ca(OH)2 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 calcium hydroxide (CAS 1305-62-0) 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 calcium hydroxide (CAS 1305-62-0)?
calcium hydroxide is polar. The bond dipoles do not cancel, so the molecule is polar, but no magnitude is quoted because the species is ionic or carries a net charge, so the dipole depends on the choice of origin and is not a molecular constant.
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: 0.2 % at 32 °F (NIOSH, 2024). No calculated partition coefficient is quoted, because the Crippen parameter set does not cover every element in the molecule.
Grade, assay basis, water content, the declared impurity profile, packaging and the transport classification, plus the regulatory status required for the destination market. PubChem’s GHS record for this substance lists H314 (22.4%): Causes severe skin burns and eye damage [Danger Skin corrosion/irritation] and H315 (45.3%): Causes skin irritation [Warning Skin corrosion/irritation].
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