{"product_id":"sodium-thiosulfate-0-1-n-1-gallon-st1250-38-zs0823-128","title":"Sodium Thiosulfate 0.1 N Solution, 1 Gallon","description":"\u003cul\u003e\n\u003cli\u003e\n\u003cstrong\u003eWhat it is.\u003c\/strong\u003e This sodium thiosulfate solution is a 0.1 N (0.1 M) volumetric titrant, supplied in a 1 gallon size. It is the standard reductant for iodometric titrations, used to measure iodine released by oxidizing analytes.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eHow iodometry works.\u003c\/strong\u003e In iodometric methods, an oxidizing analyte reacts with excess potassium iodide to release iodine, which is then titrated with thiosulfate: 2 S2O3²⁻ + I2 → S4O6²⁻ + 2 I⁻. Starch indicator, added near the endpoint, turns blue-black with iodine and goes colorless when all iodine is consumed.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eMolar equals normal.\u003c\/strong\u003e Each thiosulfate ion gives up one electron in this reaction, so for iodometry its normality equals its molarity, and its equivalent weight equals its formula weight.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eStandardization.\u003c\/strong\u003e Standardize thiosulfate against primary standards that release a known amount of iodine from iodide, such as potassium iodate or potassium dichromate. Restandardize periodically, since thiosulfate solutions slowly change strength.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eStability.\u003c\/strong\u003e Thiosulfate solutions decompose slowly due to bacterial action, light, and acidity, which can deposit sulfur and reduce strength. Clean storage and occasional restandardization keep results reliable.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eDissolved oxygen by Winkler.\u003c\/strong\u003e In the Winkler method, dissolved oxygen oxidizes manganese(II) to a higher oxidation state in alkaline solution. Upon acidification with iodide, an equivalent amount of iodine is released and titrated with thiosulfate, yielding dissolved oxygen in mg\/L.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eWhat each milliliter titrates.\u003c\/strong\u003e One milliliter of 0.1 N thiosulfate reacts with 0.1 milliequivalent, equal to 12.69 mg of iodine, 3.545 mg of chlorine as Cl2, or 0.800 mg of dissolved oxygen (calculated from equivalent weights).\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eCalculating results.\u003c\/strong\u003e Analyte mass equals the titrant volume multiplied by the standardized normality and by the analyte's milliequivalent weight. For available chlorine as Cl2, that weight is 35.45 mg per milliequivalent; for dissolved oxygen, 8.00 mg.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eCommon determinations.\u003c\/strong\u003e Thiosulfate titrations measure residual chlorine and available chlorine in bleach, dissolved oxygen by the Winkler method, peroxide value of fats and oils, copper in alloys, and many other oxidants. Pair it with Lab Pro's Potassium Iodide 10% (w\/v) Solution, 1 Quart, and Starch Indicator Solution 1%, 1 Gallon.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eWhere it is used.\u003c\/strong\u003e Laboratories use 0.1 N sodium thiosulfate in water and wastewater testing, food analysis, bleach and disinfectant QC, metal assays, and teaching labs demonstrating iodometric titration. The 1 gallon size supports daily testing.\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003ch4\u003eTechnical Specifications\u003c\/h4\u003e\n\u003ctable style=\"width:100%; border-collapse:collapse; border:1px solid #cfcfcf; margin-bottom:28px;\"\u003e\n\u003ctbody\u003e\n\u003ctr\u003e\n\u003ctd style=\"border:1px solid #cfcfcf; padding:8px 12px; vertical-align:top; text-align:left; width:32%; background:#f5f5f5;\"\u003e\u003cstrong\u003eChemical Name\u003c\/strong\u003e\u003c\/td\u003e\n\u003ctd style=\"border:1px solid #cfcfcf; padding:8px 12px; vertical-align:top; text-align:left;\"\u003e\u003cstrong\u003eSodium thiosulfate, aqueous volumetric solution\u003c\/strong\u003e\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd style=\"border:1px solid #cfcfcf; padding:8px 12px; vertical-align:top; text-align:left; width:32%; background:#f5f5f5;\"\u003e\u003cstrong\u003eCAS Numbers\u003c\/strong\u003e\u003c\/td\u003e\n\u003ctd style=\"border:1px solid #cfcfcf; padding:8px 12px; vertical-align:top; text-align:left;\"\u003e\u003cstrong\u003e10102-17-7 (sodium thiosulfate pentahydrate) or 7772-98-7 (anhydrous), per SDS; 7732-18-5 (water)\u003c\/strong\u003e\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd style=\"border:1px solid #cfcfcf; padding:8px 12px; vertical-align:top; text-align:left; width:32%; background:#f5f5f5;\"\u003e\u003cstrong\u003eSynonyms\u003c\/strong\u003e\u003c\/td\u003e\n\u003ctd style=\"border:1px solid #cfcfcf; padding:8px 12px; vertical-align:top; text-align:left;\"\u003e\u003cstrong\u003eSodium hyposulfite, hypo\u003c\/strong\u003e\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd style=\"border:1px solid #cfcfcf; padding:8px 12px; vertical-align:top; text-align:left; width:32%; background:#f5f5f5;\"\u003e\u003cstrong\u003eFormula (active)\u003c\/strong\u003e\u003c\/td\u003e\n\u003ctd style=\"border:1px solid #cfcfcf; padding:8px 12px; vertical-align:top; text-align:left;\"\u003e\u003cstrong\u003eNa2S2O3 (pentahydrate Na2S2O3·5H2O)\u003c\/strong\u003e\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd style=\"border:1px solid #cfcfcf; padding:8px 12px; vertical-align:top; text-align:left; width:32%; background:#f5f5f5;\"\u003e\u003cstrong\u003eFormula Weight\u003c\/strong\u003e\u003c\/td\u003e\n\u003ctd style=\"border:1px solid #cfcfcf; padding:8px 12px; vertical-align:top; text-align:left;\"\u003e\u003cstrong\u003e248.18 g\/mol (pentahydrate); 158.11 g\/mol (anhydrous)\u003c\/strong\u003e\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd style=\"border:1px solid #cfcfcf; padding:8px 12px; vertical-align:top; text-align:left; width:32%; background:#f5f5f5;\"\u003e\u003cstrong\u003eEquivalent Weight\u003c\/strong\u003e\u003c\/td\u003e\n\u003ctd style=\"border:1px solid #cfcfcf; padding:8px 12px; vertical-align:top; text-align:left;\"\u003e\u003cstrong\u003eFormula weight (molar = normal in iodometry)\u003c\/strong\u003e\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd style=\"border:1px solid #cfcfcf; padding:8px 12px; vertical-align:top; text-align:left; width:32%; background:#f5f5f5;\"\u003e\u003cstrong\u003eConcentration\u003c\/strong\u003e\u003c\/td\u003e\n\u003ctd style=\"border:1px solid #cfcfcf; padding:8px 12px; vertical-align:top; text-align:left;\"\u003e\u003cstrong\u003e0.1 N (0.1 M)\u003c\/strong\u003e\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd style=\"border:1px solid #cfcfcf; padding:8px 12px; vertical-align:top; text-align:left; width:32%; background:#f5f5f5;\"\u003e\u003cstrong\u003eContent\u003c\/strong\u003e\u003c\/td\u003e\n\u003ctd style=\"border:1px solid #cfcfcf; padding:8px 12px; vertical-align:top; text-align:left;\"\u003e\u003cstrong\u003eAbout 24.82 g\/L as pentahydrate (calculated)\u003c\/strong\u003e\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd style=\"border:1px solid #cfcfcf; padding:8px 12px; vertical-align:top; text-align:left; width:32%; background:#f5f5f5;\"\u003e\u003cstrong\u003eTitration Equivalence\u003c\/strong\u003e\u003c\/td\u003e\n\u003ctd style=\"border:1px solid #cfcfcf; padding:8px 12px; vertical-align:top; text-align:left;\"\u003e\u003cstrong\u003e1.00 mL = 12.69 mg I2; 3.545 mg Cl2; 0.800 mg O2 (calculated)\u003c\/strong\u003e\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd style=\"border:1px solid #cfcfcf; padding:8px 12px; vertical-align:top; text-align:left; width:32%; background:#f5f5f5;\"\u003e\u003cstrong\u003eIndicator\u003c\/strong\u003e\u003c\/td\u003e\n\u003ctd style=\"border:1px solid #cfcfcf; padding:8px 12px; vertical-align:top; text-align:left;\"\u003e\u003cstrong\u003eStarch, added near endpoint\u003c\/strong\u003e\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd style=\"border:1px solid #cfcfcf; padding:8px 12px; vertical-align:top; text-align:left; width:32%; background:#f5f5f5;\"\u003e\u003cstrong\u003ePrimary Standards\u003c\/strong\u003e\u003c\/td\u003e\n\u003ctd style=\"border:1px solid #cfcfcf; padding:8px 12px; vertical-align:top; text-align:left;\"\u003e\u003cstrong\u003ePotassium iodate; potassium dichromate\u003c\/strong\u003e\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd style=\"border:1px solid #cfcfcf; padding:8px 12px; vertical-align:top; text-align:left; width:32%; background:#f5f5f5;\"\u003e\u003cstrong\u003eAppearance\u003c\/strong\u003e\u003c\/td\u003e\n\u003ctd style=\"border:1px solid #cfcfcf; padding:8px 12px; vertical-align:top; text-align:left;\"\u003e\u003cstrong\u003eClear, colorless liquid\u003c\/strong\u003e\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd style=\"border:1px solid #cfcfcf; padding:8px 12px; vertical-align:top; text-align:left; width:32%; background:#f5f5f5;\"\u003e\u003cstrong\u003eStability Note\u003c\/strong\u003e\u003c\/td\u003e\n\u003ctd style=\"border:1px solid #cfcfcf; padding:8px 12px; vertical-align:top; text-align:left;\"\u003e\u003cstrong\u003eProtect from light, acid, and microbial contamination\u003c\/strong\u003e\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd style=\"border:1px solid #cfcfcf; padding:8px 12px; vertical-align:top; text-align:left; width:32%; background:#f5f5f5;\"\u003e\u003cstrong\u003ePackage Size\u003c\/strong\u003e\u003c\/td\u003e\n\u003ctd style=\"border:1px solid #cfcfcf; padding:8px 12px; vertical-align:top; text-align:left;\"\u003e\u003cstrong\u003e1 gallon\u003c\/strong\u003e\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003c\/tbody\u003e\n\u003c\/table\u003e\n\u003ch4\u003eApplications \/ Common Uses\u003c\/h4\u003e\n\u003cul\u003e\n\u003cli\u003e\n\u003cstrong\u003eResidual chlorine:\u003c\/strong\u003e Titrates iodine released by chlorine.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eDissolved oxygen:\u003c\/strong\u003e Completes the Winkler titration.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003ePeroxide value:\u003c\/strong\u003e Measures peroxides in fats and oils.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eBleach assay:\u003c\/strong\u003e Determines available chlorine.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eCopper assays:\u003c\/strong\u003e Titrates iodine released by copper(II).\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003ch4\u003eStorage, Handling \u0026amp; Shipping\u003c\/h4\u003e\n\u003cp\u003eStore tightly closed at room temperature, protected from light, acids, and oxidizers. Thiosulfate solutions slowly decompose through bacterial action and in acidic conditions, depositing sulfur, so keep them clean, avoid contamination, and re-standardize periodically.\u003c\/p\u003e\n\u003cul\u003e\n\u003cli\u003e\n\u003cstrong\u003eIncompatible materials:\u003c\/strong\u003e Acids (release sulfur dioxide and sulfur), strong oxidizers, and iodine.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003ePersonal protection:\u003c\/strong\u003e Safety glasses and gloves.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eSpill response:\u003c\/strong\u003e Wipe up and rinse the area with water.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eFirst aid:\u003c\/strong\u003e Eyes: rinse with water for several minutes.\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003ch4\u003eRelated Categories \u0026amp; Services\u003c\/h4\u003e\n\u003cul\u003e\n\u003cli\u003eShop \u003ca href=\"https:\/\/labproinc.com\/pages\/buffers-standards-solutions\" target=\"_blank\" rel=\"noopener noreferrer\"\u003eBuffers, Standards \u0026amp; Solutions\u003c\/a\u003e for related products in this category.\u003c\/li\u003e\n\u003cli\u003eExplore \u003ca href=\"https:\/\/labproinc.com\/collections\/inorganic-chemicals\" target=\"_blank\" rel=\"noopener noreferrer\"\u003eInorganic Chemicals\u003c\/a\u003e and \u003ca href=\"https:\/\/labproinc.com\/collections\/acs-grade-laboratory-chemicals\" target=\"_blank\" rel=\"noopener noreferrer\"\u003eACS Grade Laboratory Chemicals\u003c\/a\u003e.\u003c\/li\u003e\n\u003cli\u003e\n\u003ca href=\"https:\/\/labproinc.com\/pages\/be-a-lab-pro-vmi-program\" target=\"_blank\" rel=\"noopener noreferrer\"\u003eVendor Managed Inventory (VMI) Program\u003c\/a\u003e: Lab Pro can stock, track, and replenish this item on site so it never runs out. Contact info@labproinc.com or 888-452-2776 to set up a VMI assessment.\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003ch4\u003eRelated Articles\u003c\/h4\u003e\n\u003cul\u003e\n\u003cli\u003e\u003ca href=\"https:\/\/labproinc.com\/blogs\/news\/quantitative-analysis\" target=\"_blank\" rel=\"noopener noreferrer\"\u003eTitration Methods for Precise Chemical Analysis in Labs\u003c\/a\u003e\u003c\/li\u003e\n\u003cli\u003e\u003ca href=\"https:\/\/labproinc.com\/blogs\/chemicals-and-solvents\/ranking-oxidizing-agents-strongest-to-weakest-which-is-best-for-which-tasks\" target=\"_blank\" rel=\"noopener noreferrer\"\u003eRanking Oxidizing Agents Strongest to Weakest: Which is Best For Which Tasks?\u003c\/a\u003e\u003c\/li\u003e\n\u003cli\u003e\u003ca href=\"https:\/\/labproinc.com\/blogs\/chemicals-and-solvents\/the-importance-of-deionized-water-in-laboratory-applications\" target=\"_blank\" rel=\"noopener noreferrer\"\u003eThe Importance of Deionized Water in Laboratory Applications\u003c\/a\u003e\u003c\/li\u003e\n\u003c\/ul\u003e","brand":"Lab Pro Inc","offers":[{"title":"Default Title","offer_id":67674936246421,"sku":"ZS0823-128","price":53.26,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0757\/2327\/6437\/files\/MainImage_9ece57dd-507c-4243-9559-e503030f6cee.png?v=1791556862","url":"https:\/\/labproinc2.myshopify.com\/products\/sodium-thiosulfate-0-1-n-1-gallon-st1250-38-zs0823-128","provider":"Lab Pro Inc Plus","version":"1.0","type":"link"}