{"product_id":"methyl-orange-0-1-w-v-aqueous-500ml-mo4191-500-zm1264-16","title":"Methyl Orange Indicator, 0.1% (w\/v) Aqueous, 500 mL","description":"\u003cul\u003e\n\u003cli\u003e\n\u003cstrong\u003eWhat it is.\u003c\/strong\u003e This methyl orange indicator is a 0.1% (w\/v) aqueous solution of methyl orange, supplied in a 500 mL size. It is a ready-to-use acid-base indicator for titrations whose endpoints fall in the acidic range.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eHow the color change works.\u003c\/strong\u003e Methyl orange is red below about pH 3.1 and yellow above about pH 4.4, passing through orange in between. With a pKa of about 3.47, it changes color in the range where strong acids neutralize weak bases.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eChemical identity.\u003c\/strong\u003e Methyl orange is the sodium salt of 4-[4-(dimethylamino)phenylazo]benzenesulfonic acid (CAS 547-58-0, C14H14N3NaO3S, 327.33 g\/mol), an azo dye. In acid, protonation shifts its light absorption, producing the red form.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eWhere its endpoint is useful.\u003c\/strong\u003e Because it changes color between pH 3.1 and 4.4, methyl orange suits titrations of weak bases, such as ammonia or carbonate, with strong acids. It is a classic indicator for total alkalinity and for titrating sodium carbonate with hydrochloric acid.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eTotal alkalinity.\u003c\/strong\u003e In water analysis, alkalinity titrated to the methyl orange endpoint (near pH 4.5) represents total alkalinity: hydroxide, carbonate, and bicarbonate combined. Phenolphthalein, by contrast, marks the higher pH endpoint near 8.3.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eTwo-endpoint alkalinity.\u003c\/strong\u003e In a full alkalinity analysis, analysts first titrate the sample to the phenolphthalein endpoint near pH 8.3, then continue to the methyl orange endpoint near pH 4.5. The two volumes let analysts calculate hydroxide, carbonate, and bicarbonate separately.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eReading the endpoint.\u003c\/strong\u003e The orange transition can be hard to judge in dilute or colored samples. For a sharper endpoint, many labs use modified methyl orange, which adds a blue dye to give a gray endpoint; see Lab Pro's Modified Methyl Orange Indicator #2.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eUsing the indicator.\u003c\/strong\u003e Add two or three drops per titration, titrate to the color change, and use the same number of drops for blanks and standards. Pair it with a standard acid such as Lab Pro's Hydrochloric Acid 0.1 N (0.1 M), 1 Gallon.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eWhere it is used.\u003c\/strong\u003e Methyl orange is used in water and wastewater alkalinity testing, acid-base titrations in teaching and QC labs, carbonate and ammonia determinations, and demonstrations of pH indicator chemistry.\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\u003eMethyl orange, aqueous indicator 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\u003e547-58-0 (methyl orange, sodium salt); 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\u003eOrange III, helianthin, sodium 4-[4-(dimethylamino)phenylazo]benzenesulfonate\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 (dye)\u003c\/strong\u003e\u003c\/td\u003e\n\u003ctd style=\"border:1px solid #cfcfcf; padding:8px 12px; vertical-align:top; text-align:left;\"\u003e\u003cstrong\u003eC14H14N3NaO3S\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\u003eMolecular Weight (dye)\u003c\/strong\u003e\u003c\/td\u003e\n\u003ctd style=\"border:1px solid #cfcfcf; padding:8px 12px; vertical-align:top; text-align:left;\"\u003e\u003cstrong\u003e327.33 g\/mol\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% (w\/v)\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\u003eTransition Range\u003c\/strong\u003e\u003c\/td\u003e\n\u003ctd style=\"border:1px solid #cfcfcf; padding:8px 12px; vertical-align:top; text-align:left;\"\u003e\u003cstrong\u003epH 3.1 (red) to 4.4 (yellow)\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\u003epKa\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 3.47 (25 °C)\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\u003eTypical Endpoint\u003c\/strong\u003e\u003c\/td\u003e\n\u003ctd style=\"border:1px solid #cfcfcf; padding:8px 12px; vertical-align:top; text-align:left;\"\u003e\u003cstrong\u003eNear pH 4.5 (total alkalinity)\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\u003eOrange 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\u003ePhysical State\u003c\/strong\u003e\u003c\/td\u003e\n\u003ctd style=\"border:1px solid #cfcfcf; padding:8px 12px; vertical-align:top; text-align:left;\"\u003e\u003cstrong\u003eLiquid, aqueous 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\u003eTypical Dose\u003c\/strong\u003e\u003c\/td\u003e\n\u003ctd style=\"border:1px solid #cfcfcf; padding:8px 12px; vertical-align:top; text-align:left;\"\u003e\u003cstrong\u003e2 to 3 drops per titration\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\u003eHazard Profile\u003c\/strong\u003e\u003c\/td\u003e\n\u003ctd style=\"border:1px solid #cfcfcf; padding:8px 12px; vertical-align:top; text-align:left;\"\u003e\u003cstrong\u003eLow at indicator strength; dye is mutagenic as a solid (confirm on SDS)\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\u003e500 mL\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\u003eTotal alkalinity:\u003c\/strong\u003e Marks the total alkalinity endpoint near pH 4.5.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eCarbonate titration:\u003c\/strong\u003e Indicates sodium carbonate titrations with strong acid.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eAmmonia determination:\u003c\/strong\u003e Signals weak-base titration endpoints.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eTeaching labs:\u003c\/strong\u003e Demonstrates acid-base indicator behavior.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eQC titrations:\u003c\/strong\u003e Supports routine acid-base assays.\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 and away from strong oxidizers and strong acids. Dispense small amounts into a clean container for use, and never return used indicator to stock.\u003c\/p\u003e\n\u003cul\u003e\n\u003cli\u003e\n\u003cstrong\u003eIncompatible materials:\u003c\/strong\u003e Strong oxidizers and strong acids.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003ePersonal protection:\u003c\/strong\u003e Safety glasses and gloves; the dye stains skin and surfaces.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eSpill response:\u003c\/strong\u003e Wipe up with absorbent material 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. Skin: wash with soap and water.\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\/ph-buffers-test-kits\" target=\"_blank\" rel=\"noopener noreferrer\"\u003ePH Buffers \u0026amp; Test Kits\u003c\/a\u003e and \u003ca href=\"https:\/\/labproinc.com\/collections\/general-chemistry\" target=\"_blank\" rel=\"noopener noreferrer\"\u003eGeneral Chemistry\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\/news\/strong-acids-vs-weak-acids\" target=\"_blank\" rel=\"noopener noreferrer\"\u003eStrong Acids vs. Weak Acids: Complete Lab Safety Guide\u003c\/a\u003e\u003c\/li\u003e\n\u003cli\u003e\u003ca href=\"https:\/\/labproinc.com\/blogs\/chemicals-and-solvents\/what-is-an-acid-definition-types-examples-uses-facts\" target=\"_blank\" rel=\"noopener noreferrer\"\u003eWhat Is an Acid? Definition, Types, Examples \u0026amp; Uses\u003c\/a\u003e\u003c\/li\u003e\n\u003c\/ul\u003e","brand":"Lab Pro Inc","offers":[{"title":"Default Title","offer_id":67674936279189,"sku":"ZM1264-16","price":21.5,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0757\/2327\/6437\/files\/MainImage_275dd0ee-473a-403f-b751-3ebf6532192f.png?v=1791889682","url":"https:\/\/labproinc2.myshopify.com\/products\/methyl-orange-0-1-w-v-aqueous-500ml-mo4191-500-zm1264-16","provider":"Lab Pro Inc Plus","version":"1.0","type":"link"}