Chlorine: Characteristics
Why chlorine moves as a pressurised liquid
What this tab covers The physical and chemical properties that set its grade, price and uses, with the commercial grades and the standards that define them.Chlorine is a yellow-green gas that liquefies at minus 34 C or under about 7 bar at room temperature, which is why it moves as a pressurised liquid. Moisture makes it very corrosive, so it is dried before compression. Purity matters for water treatment and for catalysts in downstream units.
Properties that matter commercially
| Property | Value / specification | Why it matters | Source |
|---|---|---|---|
| Purity | liquid chlorine at least 99.5% Cl2 (IS 646) | water treatment and food uses require low impurities | BIS IS 646 |
| Moisture | below about 50 ppm (indicative) | wet chlorine corrodes steel | indicative |
| Nitrogen trichloride | kept at ppm levels | NCl3 is explosive and concentrates in liquid chlorine | Euro Chlor safety guidance (indicative) |
| Boiling point and vapour pressure | minus 34 C; about 6.8 bar at 20 C | sets container design | standard property |
Commercial grades
- Liquid chlorine in tonners and cylinders (water treatment, IS 646)
- Pipeline gaseous chlorine (captive)
- Electronic-grade chlorine for semiconductor etching (high purity)