Assembly Line

How chlorine is made

Table salt dissolved in water and hit with a huge electric current gives off chlorine.

stations
5
things upstream
5
raw sources
4
steps from the ground
2

The short version

Chlorine is made by passing electric current through salt brine in a cell split by a membrane. Chlorine gas collects at one electrode. At the other, hydrogen gas and caustic soda form. The chlorine is cooled, dried and compressed into a liquid. Every tonne made brings along a fixed amount of caustic soda.

  1. Dissolve salt into brine

    Salt is dissolved in water to make a saturated brine. Some plants dissolve rock salt underground and pump the brine out to the surface.

    Goes in
    Rock saltWater

  2. Purify the brine

    Chemicals precipitate calcium, magnesium and other contaminants, and filters and ion-exchange beds take out the rest. Dirty brine ruins the cell membranes.

  3. Run current through the cells

    In each membrane cell, chloride ions give up electrons at the anode and become chlorine gas. Only sodium ions can pass through the membrane, and at the cathode water breaks into hydrogen gas and hydroxide.

  4. Cool and dry the chlorine

    Hot, wet chlorine leaves the cells and is cooled to remove most of its water. It is then dried by contact with concentrated sulfuric acid.

    Goes in
    Sulfuric acid

  5. Compress and liquefy it

    The dry gas is compressed and chilled until it condenses. Liquid chlorine is stored in pressure tanks and shipped in tank cars, or piped to plants next door.

End of the lineChlorine Next it goes into bleach, pvc, polycarbonate and 12 more.

Worth repeating

  • Splitting salt water also gives off hydrogen, one mole of it for every mole of chlorine.
  • The process uses about 2,500 kWh of electricity for each tonne of caustic soda it makes.
  • Roughly two-thirds of chlorine ends up in organic chemicals such as PVC, and the finished products often contain no chlorine at all.

Back to the ground

Follow every input upstream and chlorine starts as these 4 raw sources.

Rock saltWaterSulfurAir

Everything it is made of See it on the map

Open the whole family tree

Where it goes next

Chlorine feeds 15 lines directly and reaches 311 things in total.

BleachPVCPolycarbonateEpoxyPolyurethanePTFEKevlarTitanium dioxideNitrile gloveTitaniumGoldHydrochloric acidRefrigerantSpandexIridium

Everything made from it

Further down the line
Kitchen spongeCredit cardPlastic wrapDishwasherGarden hoseAmerican footballVolleyballYoga matAction figureFashion dollDesk globeInflatable pool toyChain-link fencePVC pipeVinyl flooringPower cableSmoke detectorFlip-flopsUSB cableVinyl recordLED light bulbCamera droneEyeglass lensSunglassesBike helmetBlenderHard-shell suitcaseSmartwatchWireless earbudsPhone chargerDigital cameraCamera lensCompact discVideo game consoleDigital thermometerPrinted circuit boardWind turbineElectric motorRebarAluminum canAirlinerSurfboardSkiSnowboardTennis racketFishing rodProsthetic legLoudspeakerUmbrellaAdhesive bandagePacemakerRefrigeratorCarSkateboardGolf ballSoccer ballHardwood flooringWater heaterSofaOffice chairRoller skatesBowling ballWheelchairUnderwearLeggingsSwimsuitRaincoatBackpackSneakerMattressRazor bladeNonstick panBrake padCanoeToothpasteSunscreenLipstickNail polishPaintCrayonEraserCandy-coated chocolateFoundation makeupE-readerHip implantJet engineDrill bitMicrochipLEDSewing needleGold ringFountain penGold barOlympic-style medalDeodorantAir conditionerAsthma inhalerAA batteryMicrowave popcornCandy caneEyeglass frameDuct tapeElectric car batteryPencilNailFiberglass insulationWindshieldAcoustic guitarPianoViolinDrum kitTennis ballBaseballBasketballPaper strawPaper bagPizza boxLaminate flooringWooden chairWooden doorClear adhesive tapeStapleIce skatesGolf clubCricket batDartboardChess setKiteBoard gameJigsaw puzzleUkuleleCelloDrumstickSnow globePinball machineSanitary padCotton swabAsphalt shingleDouble-glazed windowSailboatDress shirtTailored suitLeather handbagLeather walletHiking bootsHigh heelsMicrophoneCardboard boxToilet paperBookEnvelopeSticky notesPlaying cardsMatchLeather shoeBaseball capCarpetDisposable diaperHearing aidSmartphoneLaptopTelevisionHard driveSolid-state driveComputer keyboardComputer mouseMicrowave ovenWashing machineSatelliteElectric carAirbagOrbital rocketLocomotiveMotorcycleElevatorCeiling fanTreadmillWi-Fi routerInkjet printerGraphics cardRemote controlElectric toothbrushVacuum cleanerSubway trainSkyscraperColaSparkling waterBeerHard ciderSodaRoot beerEnergy drinkTonic waterLight beerNon-alcoholic beerInsect repellentSyringePlastic bagTin canRubik's CubeBallpoint penPaper cupWallpaperMarker penHighlighterFlying discTrading cardsCeramic floor tileFlagNewspaperBanknoteT-shirtElectric kettleScissorsMirrorContainer shipShipping containerBicycleStainless steel water bottleBilliard ballDiceDie-cast toy carCoil springHammerWheelbarrowFire extinguisherGas cylinderNeon signSuspension bridge cableAluminum window frameLeather beltToothbrushMascaraLEGO brickLCD screenBlackboard chalkSprinklesPlastic strawPrinter tonerEyeshadowBath towelShampooCondomSolar panelContact lensWine corkPressure cookerOptical fiberFireworksCake mixHair dyeTamponSoapLaundry detergentPaperclipDonutCorn flakesCotton candyCandleJarred salsaCanned meatFish sticksZip-top bagPillowMouthwashCough syrupLight switchFacial tissueCondensed milkBaby formulaCoconut milkCanned soupPadlock3D printer filamentHeadphonesHarmonicaChampagneMemory chipCamera sensorSolar cellToffee

Keep walking

Plastic bag 6 stations · 17 raw sources Tortilla 7 stations · 12 raw sources Power cable 9 stations · 10 raw sources Frozen pizza 8 stations · 16 raw sources Margarine 7 stations · 9 raw sources Lollipop 6 stations · 5 raw sources

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Sources

Cite this page: "How chlorine is made." Assembly Line, 2026-11-03. https://assemblyline.org/make/chlorine

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