Direct comparison
Sodium Hypochlorite vs Calcium Hypochlorite
Sodium vs calcium hypochlorite: liquid vs solid form, formula, solubility and heat hazards, plus the disinfection limits CDC says both share.
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How do Sodium hypochlorite and Calcium hypochlorite compare side by side?
The table below compares Sodium hypochlorite and Calcium hypochlorite across 10 dimensions, from formula and molecular weight to when each is described.
Side-by-side comparison
| Dimension | Sodium hypochlorite | Calcium hypochlorite |
|---|---|---|
| Formula and molecular weight | NaClO (PubChem formula ClNaO), molecular weight 74.44. | Ca(ClO)2 (PubChem formula CaCl2O2; IUPAC name calcium dihypochlorite), molecular weight 142.98. |
| Physical form | Colorless or slightly yellow watery liquid with an odor of household bleach; mixes with water (USCG CHRIS). | White granular solid, or tablets compressed from the granules, with an odor of chlorine (PubChem). |
| How CDC classes it | The liquid hypochlorite. The most prevalent chlorine products in the United States are aqueous solutions of 5.25%-6.15% sodium hypochlorite, usually called household bleach (CDC). | The solid hypochlorite. CDC names it as the solid example alongside liquid sodium hypochlorite and gives no concentration for it. |
| Solubility in water | 293 g/L at 20 C (ICSC). | 21 g/100 mL at 25 C (Kirk-Othmer / ICSC, via PubChem). |
| Heat, fire and decomposition | The anhydrous solid obtained from the pentahydrate may decompose violently on heating or friction (Bretherick, via HSDB). That note is about the solid, not about the liquid solutions described above. | Noncombustible but accelerates the burning of combustible materials; decomposes at 100 C (ICSC); the 70% grade may decompose violently if exposed to heat or direct sunlight (USCG CHRIS). |
| Disinfection advantages (CDC, hypochlorites as a group) | Broad spectrum of antimicrobial activity, no toxic residues, unaffected by water hardness, inexpensive and fast acting. | The same group-level advantages: CDC lists them for hypochlorites, not for one compound. |
| Disinfection limits (CDC, hypochlorites as a group) | Corrosive to metals at high concentrations (above 500 ppm), inactivated by organic matter, bleaches fabrics. Household bleach at 5.25%-6.15% can cause ocular irritation or oropharyngeal, esophageal and gastric burns. | The same group-level limits apply to hypochlorites, so a solid form does not remove them. |
| Mixing hazard | Releases toxic chlorine gas when mixed with ammonia or acid (CDC). | Same hazard: CDC states it for hypochlorites generally. |
| Effect of pH on efficacy | CDC: the disinfecting efficacy of chlorine decreases as pH increases; the activity is attributed to undissociated hypochlorous acid (HOCl). | Same principle: it applies to hypochlorites generally. |
| When each is described | Pick sodium hypochlorite when a ready liquid (household-bleach type) is what the procedure calls for. | Pick calcium hypochlorite when a solid (granules or tablets) is what the procedure calls for. In both cases follow your facility's written procedure and the product label. |
Sources
- CDC, Guideline for Disinfection and Sterilization in Healthcare Facilities (2008, updated June 2024), "Chlorine and Chlorine Compounds"
- NIH PubChem records for calcium hypochlorite (CID 24504) and sodium hypochlorite (CID 23665760)
- ICSC and USCG CHRIS data as reproduced in PubChem. Read 2026-10-30
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Common questions
Common questions about Sodium hypochlorite vs Calcium hypochlorite
What is the difference between sodium hypochlorite and calcium hypochlorite?
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Sodium hypochlorite (NaClO, molecular weight 74.44) is a liquid, the active ingredient in household bleach. Calcium hypochlorite (Ca(ClO)2, molecular weight 142.98) is a white granular solid or compressed tablet. CDC describes both as hypochlorites with the same disinfection advantages and limits, so the difference is mainly physical form, solubility and heat hazards.
Going deeper
