“Sodium carbonate, light” and “soda ash, light” are the same material under two names. This page covers substance identity, the assay basis, and the dissolution and blending behaviour that decides when the light grade is the right specification. Properties in full and the application list are on the light soda ash page.
Substance identity
| Field | Value |
|---|---|
| Systematic name | Sodium carbonate |
| Formula | Na2CO3 |
| CAS number | 497-19-8 |
| PubChem CID | 10340 |
| EC number | 207-838-8 |
| Molar mass | 105.99 g/mol |
| Calculated sodium content | approx. 43.4 % Na |
Synonyms for this exact material: soda ash light, light ash, calcined soda, anhydrous sodium carbonate, disodium carbonate. “Washing soda” normally denotes the decahydrate and should not be used here. Sodium bicarbonate (NaHCO3, CAS 144-55-8) is a different substance, not a grade of this one.
Specification
Typical commercial values, not guaranteed limits.
| Specification element | Light grade | Comment |
|---|---|---|
| Bulk density | approx. 0.50–0.60 t/m3 | the parameter that defines the grade |
| Particle size | predominantly below approx. 0.15–0.2 mm | request the sieve analysis |
| Assay, total alkali as Na2CO3 | 99.2 % min typical, dry basis | same basis as dense grade |
| Loss on heating | typically ≤ 0.5–1.0 % | |
| NaCl | typically ≤ 0.3–0.8 % | route-dependent |
| Iron as Fe2O3 | typically ≤ 0.0035–0.01 % |
Selection logic in one line: if the material will be dissolved or blended into a fine powder, specify light; if it will be conveyed, weighed and melted as part of a coarse dry batch, specify dense. Assay does not distinguish them, so bulk density and sieve limits must appear in the purchase specification as pass/fail criteria, with the measurement method named.
Properties
Substance constants, grade-independent: melting point approx. 851 °C; true density approx. 2.53–2.54 g/cm3; solubility approx. 21.5 g/100 g water at 20 °C, with a maximum near 35 °C; 1 % solution pH approx. 11.3–11.6; dissolution exothermic.
Grade-dependent: high specific surface area gives rapid dissolution and rapid reaction, and equally rapid moisture uptake and caking. The material is cohesive and aeratable, so it flows poorly compared with dense grade and requires flow aids in silo service.
Applications
Selected wherever dissolution rate or fine-powder blending governs: detergent and cleaner formulation, chemical manufacture of sodium salts, water treatment and softening, pulp and paper, textile scouring and reactive dyeing, effluent and flue-gas neutralisation. Full treatment on the light soda ash page.
Handling and storage
Alkaline; dust and solutions irritate eyes, skin and respiratory tract; eye protection, gloves and dust control required; the safety data sheet governs. Dust generation is the grade’s principal hygiene issue — enclose transfers and extract at source.
Hygroscopic and strongly cake-prone; store sealed, dry, off the floor, away from condensation cycles; rotate stock. Expect bridging and rat-holing in hoppers; do not assume dense-grade silo geometry will work.
Incompatible with acids (CO2 evolution, heat) and with aluminium and zinc in moist conditions (alkaline attack, hydrogen). Add solid to water with agitation, never water to a bulk of solid.
Notes
- This page and the light soda ash page describe one product. Under the accepted plan this URL is a 301, not a page.
- Regulatory identity (inventories, SDS, transport) is CAS 497-19-8 irrespective of grade. Grade is a commercial and physical descriptor, not part of substance identity.
- Light grade left in humid storage loses assay slowly through carbonation and hydration; check long-held stock before assay-critical use.